1.
Hypofractionated stereotactic body radiation therapy (SBRT) of 60 Gy in 3 fractions is most appropriate for a patient who has medically inoperable NSCLC with a: A. B. C. D.
3-cm tumor involving the chest wall. 3-cm tumor involving the right mainstem bronchus. 2-cm tumor involving the right lower lobe with hilar adenopathy. 2-cm tumor involving the carina.
Correct answer is A. RATIONALE: The ineligibility for RTOG stereotactic body radiation therapy (SBRT) trial: Patients with T2 or T3 primary tumors of >5 cm or patients with T3 primary tumors involving the central chest and structures of the mediastinum. The primary tumor of any T-stage within or touching the zone of the proximal bronchial tree defined as a volume 2 cm in all directions around the proximal bronchial tree (carina, right and left main bronchi, right and left upper lobe bronchi, intermedius bronchus, right middle lobe bronchus, lingular bronchus, right and left lower lobe bronchi). A higher rate of airway stenosis was reported in a prior doseescalating stud when 60 Gy was given in 3 fractions to tumors located in the central zone. 2.
Which of the following types of radiation has the lowest LET? A. B. C. D.
250-keV x-rays 1.25-MeV γ-rays 250-keV protons 1-MeV carbon ions
Correct answer is B. RATIONALE: The high-energy photons have the lowest LET (i.e., they set electrons in motion with a LET of 0.3-0.5 keV/µm), followed by low-energy photons (2.0-3.0 keV/µm) and low-energy protons (50-100 keV/µm). Carbon ions have the highest LET (~150 keV/µm). REFERENCES: Hall and Giaccia. Radiobiology for the Radiologist. 6th edition, Chapter 7. Tannock, Hill, Bristow, and Harrington. The Basic Science of Oncology. 4th edition, Chapter 14. 3.
Which of the following statements about microsatellite instability in colorectal cancer is FALSE? A. It accounts for about 15% of sporadic colorectal cancers and most hereditary nonpolyposis cancers. B. It is associated with a mucinous histology and a surrounding lymphoid reaction. C. These tumors tend to be more prevalent in the proximal colon. D. These tumors are associated with worse survival than stage-matched microsatellite stable tumors.
Correct answer is D. REFERENCES: Niv Y. Microsatellite instability and MLH1 promoter hypermethylation in colorectal cancer. World Journal of Gastroenterology. Mar 28, 2007;13(12):1767-9. Lynch HT, de la Chapelle A. Genetic susceptibility to nonpolyposis colorectal cancer. Journal of Medical Genetics. Nov 1999;36(11):801-18.
4.
The quantity exposure can be described as the ionization equivalent of: A. B. C. D.
radiation kerma in air. radiation kerma in tissue. collision kerma in air. collision kerma in tissue.
Correct answer is C. RATIONALE: According to its definition, exposure is a measure of ionization produced in air by photons. When compared to kerma, this is equivalent to the collisional component of kerma, which is the "kinetic energy released in a medium" when the medium in this case is air. The radiation kerma is related to the energy loss due to radiative losses (ie, bremsstrahlung). 5.
Which of the following bones is most commonly involved in patients with osteosarcoma? A. B. C. D.
Humerus Femur Spine Tibia
Correct answer is B. RATIONALE: The following bones are most commonly involved in osteosarcoma: Femur = 40%. Humerus = 15%. Tibia = 15%. Spine = <5%. REFERENCE: Halperin, et al. Pediatric Radiation Oncology. 6.
What is the threshold dose for dysphagia from radiation therapy to the superior constrictor muscles? A. B. C. D.
75 Gy 65 Gy 55 Gy 45 Gy
Correct answer is C. RATIONALE: The answer to this item is based on tolerance doses established from MSKCC and multiple ASTRO 2007 abstracts.
7.
Which of the following statements about the ECOG study evaluating the locoregional failure rate in patients with breast cancer and positive lymph nodes 10 years after undergoing mastectomy, adjuvant chemotherapy with or without tamoxifen, and no irradiation is true? A. B. C. D.
The isolated locoregional failure rate was 21%. The median number of positive lymph nodes was 3. The median number of axillary lymph nodes examined was 8. The locoregional recurrence rate was not affected by the number of axillary lymph nodes examined.
Correct answer is B. RATIONALE: The rate of isolated locoregional recurrence was 13%. The median number of positive lymph nodes was 3 (range 1 to 53). The median number of axillary lymph nodes examined was 15 (range 2 to 63). The observed rate of locoregional recurrence +/- distant failure (DF) varied by the number of nodes examined. When 2 to 5 lymph nodes were examined, the locoregional failure (LRF) +/- DF was 27.2%; 6-10 examined was 22.2% and 20% for 11 or more lymph nodes examined. The LRF for patients with 1 to 3 positive lymph nodes was 12.9%, and the LRF for patients with 4 or more positive lymph nodes was 28.7%. Multivariate analysis showed that increasing tumor size, increasing numbers of involved nodes, negative estrogen receptor status, and decreasing number of lymph nodes examined were significant for increasing the rate of LRF +/- simultaneous DF. REFERENCE: Recht, et al. Locoregional failure 10 years after mastectomy and adjuvant chemotherapy with or without tamoxifen without irradiation: experience of the ECOG. Journal of Clinical Oncology(JCO). 1999;17(6):1689-1700. 8.
Which of the following statements best describes why the single hit, multitarget survival curve model was rejected in favor of the linear quadratic model? Single-hit, multitarget model: S = 1 – (1 – e-D/D0)n Linear-quadratic model: S = e-(
αD+βD2)
A. The single-hit, multitarget model did not provide a good fit to cell survival data for high radiation doses. B. The single-hit, multitarget model did not provide a good fit to cell survival data for low radiation doses. C. The linear-quadratic model is based on Poisson statistics, but the single-hit, multitarget model was not. D. The linear-quadratic model was more robust in terms of correcting for effects of repopulation and cell-cycle redistribution. Correct answer is B. RATIONALE: The single-hit, multitarget survival curve model was ultimately rejected in favor of the linear-quadratic model because it did not account for the fact that survival curves have non-zero initial slopes. Thus, it did not provide a good fit to cell survival or tissue dose response data for the low radiation doses that are relevant to fractionated radiation therapy.
9.
Which of the following statements about staging and prognostic factors for primary malignant bone tumors is true? A. B. C. D.
MRI is best for evaluating metastatic disease in the thorax. MRI is best for staging of intraosseous or extraosseous tumors. A tumor >8 cm in greatest dimension is classified as stage T3. A worse prognosis is associated with lung metastases than with bone or hepatic metastases.
Correct answer is B. RATIONALE: Option A: CT is the exam of choice for evaluating the thorax for metastatic disease. CT is preferred over MRI for flat bones (such as the pelvis, scapula, or posterior elements of the vertebrae) where characterization of a lesion by radiography may be incomplete or difficult because of an inadequately visualized lesion. The role of CT in these circumstances is to characterize the lesion and determine whether it is potentially malignant or not. CT images may suffice for local staging. Option B: MRI provides the most accurate depiction of intraosseous or extraosseous tumors. To improve imaging in locations such as the pelvis or vertebrae, special sequences could be done. Bone scan is the exam of choice to evaluate for multiple skeletal lesions. Option C: Stage T1 = tumor 8 cm or less); stage T2 = tumor greater than 8 cm; stage T3 =discontinuous tumors in the primary bone site. Option D: Bone and hepatic metastases have a worse prognosis than lung metastases. REFERENCE: Greene FL, Page DL, Fleming ID, Fritz AG, eds. AJCC Cancer Staging Manual, 6th edition. 2002; pp. 187-190. 10.
The fluence maps for an IMRT plan are: A. B. C. D.
generated by an optimization routine that minimizes the cost function. correlated with the gantry speed function to obtain the dose volume histogram. slid into the dose kernels for a sliding-window delivery. flat to provide a uniform target dose.
Correct answer is A. RATIONALE: In inverse IMRT treatment planning, the planner defines the orientation and energies of all beams, and dose constraints for both normal structures and the target. A computer optimization algorithm is employed that attempts to meet these objectives by minimizing the difference between the current dose distribution and the desired dose distribution (cost function). Once the cost function is minimized, the optimization algorithm generates an intensity fluence for each beam. 11.
Which of the following trials demonstrated an improvement in survival for patients receiving preoperative radiation therapy for rectal cancer? A. B. C. D.
German Rectal Cancer Study Group Swedish Rectal Cancer Dutch CKVO NSABP R-01
Correct answer is B. RATIONALE: The only randomized trial that has shown a survival benefit for preoperative radiotherapy was the Swedish Trial. The German and Dutch trials did not show a survival benefit. NSABP R-01 evaluated postoperative treatment.
12.
Which of the following two chemotherapy agents would be most appropriate to administer concurrently with thoracic radiation therapy for patients with limited-stage SCLC? A. B. C. D.
Cisplatin and etoposide Cisplatin and irinotecan Carboplatin and paclitaxel Pemetrexed and carboplatin
Correct answer is A. RATIONALE: Cisplatin and etoposide remain the optimal regimen used with thoracic radiation therapy in limited-stage SCLC. Other agents tested or adding a third agent did not prove beneficial. 13.
What is the most common presentation of bladder cancer in the United States? A. B. C. D.
Bone pain Flank pain Urinary obstruction Painless hematuria
Correct answer is D. RATIONALE: Painless hematuria is the most common presentation of bladder cancer. 14.
The power of a statistical test is the probability that the null hypothesis is: A. B. C. D.
true. false. rejected when it is true. rejected when it is false.
Correct answer is D. RATIONALE: This is the definition of statistical power. 15.
Which of the following statements about radiation-induced locally multiply damaged sites (LMDS) in DNA is FALSE? A. B. C. D.
Most DNA-damaging agents produce LMDS. LMDS can consist of one or more closely spaced types of DNA damage. LMDS can be inherently more difficult to repair. High-LET radiation exposure causes an increase in both the number and complexity of LMDS per unit dose.
Correct answer is A. RATIONALE: The random and discrete nature of energy deposition and the resulting production of clustered lesions in DNA in some cases are largely unique to ionizing radiation, compared to most other DNA damaging agents. REFERENCE: Hall and Giaccia. Radiobiology for the Radiologist. 6th edition, Chapter 1 and (the beginning of) Chapter 2.
16.
What is the FIGO stage for an adenocarcinoma of the uterus with 1.3-cm-depth invasion of a 2.7-cm-thick myometrium and endocervical gland involvement but negative peritoneal washings? A. B. C. D.
IB IC IIA IIB
Correct answer is C. RATIONALE: According to FIGO staging criteria, <50% myometrial invasion (1.3/2.7 = 48%) indicates stage IB, but endocervical gland involvement indicates stage IIA. 17.
What is the best time after surgery to initiate a 7-week course of conventional fractionated radiation therapy for high-risk patients with advanced head and neck cancer? A. B. C. D.
04 weeks 08 weeks 10 weeks 12 weeks
Correct answer is A. RATIONALE: This item is based on Ang's 2004 International Journal of Radiation Oncology, Biology, Physics (IJROBP) paper showing that the optimal treatment duration is 11 weeks (ie, 7-week radiation course delivered 4 weeks after surgery = 11 weeks) for high-risk patients with advanced head and neck cancer. 18.
Which of the following findings is most characteristic of Langerhans cell histiocytosis? A. B. C. D.
Psammoma body Physaliphorous cell Homer-Wright rosette Birbeck granule
Correct answer is D. RATIONALE: Birbeck granules are characteristic of Langerhans cell histiocytosis (LCH) and can be seen on electron microscopy. Psammoma bodies are collections of calcium seen in a variety of different neoplasms; physaliphorous cells are seen with chordoma; Homer-Wright rosettes are typically seen with neuroblastoma. 19.
What happens to the angle in which isodose lines are tilted due to the presence of a wedge in a photon beam as a function of depth? A. B. C. D.
Increases Decreases Can increase or decrease Remains unchanged
Correct answer is B. RATIONALE: The presence of scattered radiation decreases with increasing depth in a phantom, thus causing the angle in which isodose lines are tilted to decrease.
20.
Which of the following statements about adenocarcinoma of the anus is FALSE? A. It typically arises within the anal mucosa or anal fistulas. B. It represents approximately 5% to 10% of all cases of anal cancer. C. It presents with more advanced disease than epidermoid carcinomas of the anal canal. D. Definitive chemoradiation results in poor local control and high distant failure rates.
Correct answer: ABCD. REFERENCES: Papagikos M, Crane CH, Skibber J, Janjan NA, Feig B, Rodriguez-Bigas MA, Hung A, Wolff RA, Delclos M, Lin E, Cleary K. Chemoradiation for adenocarcinoma of the anus. International Journal of Radiation Oncology, Biology, Physics (Int J Radiat Oncol Biol Phys). Mar 1, 2003;55(3):669-78. Basik M, Rodriguez-Bigas MA, Penetrante R, Petrelli NJ. Prognosis and recurrence patterns of anal adenocarcinoma. American Journal of Surgery. Feb 1995;169(2):233-7. 21.
Which of the following organs is believed to contain serially arranged FSUs? A. B. C. D.
Spinal cord Kidney Liver Lung
Correct answer is A. RATIONALE: Withers' functional subunit model proposes that the irradiation volume dependence of normal tissue tolerance depends in part on the structural and functional organization of tissues into functional subunits (FSUs). For some tissues, these FSUs are believed to be arranged "in series," such that the inactivation of a single unit could compromise the entire organ's function. The spinal cord is thought to contain serially arranged FSUs. For other tissues, the FSUs operate essentially independent of each other and are said to be arranged "in parallel." Such tissues, thought to include the liver, lung, and kidney, have large functional reserves and can tolerate very high radiation doses to small/medium treatment volumes. REFERENCE: Hall and Giaccia. Radiobiology for the Radiologist. 6th edition, Chapter 19. 22.
Which of the following locations of male urethral carcinoma has the worst prognosis? A. B. C. D.
Distal Prostatic Bulbomembranous Location is not prognostic.
Correct answer: ABCD. RATIONALE: Understanding basic epidemiologic information and common presentation characteristics will help the clinician determine the appropriate course of action in this relatively infrequent diagnosis. Patients with bulbomembranous involvement usually have advanced disease at presentation.
23.
Which of the following treatments should be used as first-line therapy for gastric MALT lymphoma to achieve complete tumor remission in the majority of patients? A. B. C. D.
Focal radiation field therapy after initial biopsy Combined chemotherapy and radiation therapy Antibiotic therapy for Helicobacter pylori Surgical resection combined with chemotherapy
Correct answer is C. RATIONALE: Gastric mucosa-associated lymphoid tissue (MALT) lymphoma is associated with Helicobacter pylori. More than two thirds of patients with this disease respond to antibiotic therapy, which is considered to be first-line therapy. 24.
Which of the following statements about pure bronchioloalveolar carcinoma is true? A. It is not associated with the expression of TTF-1 and CK7. B. The EGFR gene mutation in patients with lung cancer is linked to bronchioloalveolar differentiation. C. It requires the presence of lymphatic space invasion. D. Stromal invasion is commonly associated.
Correct answer is B. RATIONALE: Pure bronchioloalveolar carcinoma (BAC) requires absence of invasion of stroma, pleura, and lymphatic spaces. Nonmucinous BAC expresses TTF-1, CK7, and lacks CK20. 25.
Which of the following sites is most commonly associated with HPV-induced squamous cell carcinoma? A. B. C. D.
Hypopharynx Oropharynx Nasopharynx Larynx
Correct answer is B. Site of cancer % of +HPV-16 DNA Hypopharynx 0% Oropharynx 50% Nasopharynx 14% Larynx 3% REFERENCE: Jon Mork, et al. New England Journal of Medicine (NEJM). 2001;344,15:112531.
26.
According to AAPM TG 51, a thin lead sheet should be used in the calibration of an x-ray beam to determine the depth dose curve for all photon energies greater than: A. B. C. D.
04 MV. 06 MV. 10 MV. 15 MV.
Correct answer is C. RATIONALE: According to AAPM TG 51, for photon beams about 10 MV and above, electron contamination from the accelerator head may significantly affect the dose at dmax. To reduce the effects of these contaminant electrons to negligible levels, this task group recommends the use of a thin lead sheet when measuring the percent depth dose curve for these higher-energy photon beams. 27.
In mammalian cells, which of the following groups of proteins is involved in nonhomologous end-joining repair of DNA double-strand breaks? A. B. C. D.
Ku80, Ligase III, RPA XPC, XPE, CSA Artemis, Ku70, Ligase IV DNA PKcs, Ku70, RPA
Correct answer is C. RATIONALE: It is important to know which proteins participate in nonhomologous end-joining (NHEJ), since, when defective, one or more of these proteins could increase the cellular radiosensitivity of patients treated with radiation therapy, possibly culminating in an increased risk of normal tissue complications. Artemis (a complex of Rad50, MRE11 and NBS1, responsible for the processing of breaks), Ku70, and Ligase IV are all involved in NHEJ. Ligase III, XPC, XPE, and RPA are not involved. REFERENCE: Tannock, Hill, Bristow, and Harrington. The Basic Science of Oncology. 4th edition, Chapter 5. 28.
Which of the following statements does NOT correctly describe a characteristic of HNPCC? A. B. C. D.
It is also known as Lynch syndrome. It is the most common hereditary colorectal cancer syndrome. Current diagnostic criteria include the Amsterdam criteria. Promoter hypomethylation accounts for some cases of microsatellite instability.
Correct answer is D. REFERENCES: Hendriks YM, de Jong AE, Morreau H, Tops CM, Vasen HF, Wijnen JT, Breuning MH, Bröcker-Vriends AH. Diagnostic approach and management of Lynch syndrome (hereditary nonpolyposis colorectal carcinoma): a guide for clinicians. CA: A Cancer Journal for Clinicians (CA: Cancer J Clin). July-August 2006;56(4):213-25.
29.
Which of the following FIGO stages is most commonly associated with a lower one-third vaginal cancer that has invaded the subvaginal and parametrial tissues but not the pelvic side wall? A. B. C. D.
I II III IV
Correct answer: ABCD. RATIONALE: Stage II is the most common FIGO presentation of vaginal cancer (in the pre-MRI era), but up to 50% of patients may have III+ disease in the MRI era. The proposed FIGO subdivision of IIA (subvaginal) and IIB (parametrial) is often used by Perez. REFERENCE: Taylor. Clinical Radiology. 2007;62:549-555. 30.
What is the expected 5-year overall survival rate in a patient with muscle-invasive bladder cancer treated with TURBT, followed by combined chemotherapy and radiation therapy? A. B. C. D.
80% 65% 50% 25%
Correct answer is C. RATIONALE: According to most trials, the expected 5-year overall survival rate is approximately 50% for patients with muscle-invasive bladder cancer treated with TURBT, followed by combined chemotherapy and radiation therapy. This is similar to that of a radical cystectomy. 31.
Which of the following stages of oropharyngeal cancer can be adequately treated with unilateral therapy? A. B. C. D.
T1N1 of the tonsil T1N2a of the tonsil Lateralized T2N0 of the base of tongue T3N0 of the tonsil
Correct answer is A. RATIONALE: Based on Princess Margaret Hospital experience reported by O' Sullivan. REFERENCE: International Journal of Radiation Oncology, Biology, Physics (Int. J. Radiation Oncology Biol. Phys.). 2001;51(2):332–343.
32.
Which of the following Ann Arbor stages would be most appropriate for a 15-year-old boy who has Hodgkin lymphoma with clinical and radiographic evidence of left neck and left supraclavicular fossa lymphadenopathy, generalized pruritus, and a 7-lb weight loss over the past 6 months? A. B. C. D.
Stage IA Stage IB Stage IIA Stage IIB
Correct answer is A. RATIONALE: The neck and supraclavicular fossa constitute one region for lymphoma staging; therefore, this patient would have stage I disease. B symptoms include the following: 1) Loss of >10% weight loss over 6 months, 2) fever, 3) night sweats. Pruritus is not considered a B symptom. 33.
Compared to 3D conformal radiation therapy, an image-guided radiotherapy (IGRT) program requires: A. B. C. D.
a higher dose rate. less immobilization. more quality assurance. daily CT imaging.
Correct answer is C. RATIONALE: Image-guided radiotherapy (IGRT) requires more quality assurance (QA). Imaging systems, as well as integration between imaging and treatment systems, need to undergo more QA in addition to performing the standard QA. 34.
Which of the following secondary cancers is most likely to be induced by prior radiation therapy? A. B. C. D.
Ovarian cancer 11 years after breast-conserving therapy Angiosarcoma of the left breast 12 years after breast-conserving therapy Leukemia 2 years after chemoradiotherapy for lymphoma Adenocarcinoma of the lung in a patient who smokes and was treated for SCLC 4 years earlier
Correct answer is B. RATIONALE: Radiation-induced solid tumors typically occur in or near the previously irradiated treatment field(s) between 10 and 50 years after radiation therapy for the previous cancer.
35.
Which of the following recursive partitioning analysis (RPA) classifications and primary disease sites had an overall survival benefit based on the phase III RTOG 9508 (Andrews) trial that evaluated WBRT with and without stereotactic radiosurgery? A. B. C. D.
RPA Class I Class III Class I Class III
Primary Disease Site Lung cancer Lung cancer Breast cancer Breast cancer
Correct answer is A. RATIONALE: Based on the subgroup analysis of RPA classification and primary disease site, patients who had lung cancer and were in the RPA class I group experienced an overall survival benefit with the addition of stereotactic radiosurgery (SRS) to WBRT. Otherwise, no detectable overall survival advantage was demonstrated with the addition of SRS to WBRT. 36.
In the Norwegian (Aalders) adjuvant endometrial trial, which subset of patients may have improved overall survival for pelvic radiation after vaginal brachytherapy? A. B. C. D.
IA, grade 2 IB, grade 3 IC, grade 3 IIA, grade 3
Correct answer is C. RATIONALE: The Norwegian (Aalders, et al) trial only included patients with stage I disease. For all patients taken together, there was no overall survival benefit seen with pelvic irradiation. Patients with stage IC, grade 3 had a better overall survival (82% vs 72%) and local control (95% vs 80%) and the same distant metastasis (15%) on subset analysis. Though the number of patients with stage IC, grade 3 (approximately 10%) was too few for statistical significance for overall survival, the analysis suggests a benefit for this subgroup. REFERENCE: Aalders J, Abeler V, Kolstad P, et al. Postoperative external irradiation and prognostic parameters in stage I endometrial carcinoma: Clinical and histologic study of 540 patients. Obstetrics & Gynecology. 1980;56:419-427. 37.
Which of the following imaging studies is most useful in the local evaluation of solitary plasmacytoma of the bone? A. B. C. D.
MRI CT scan Bone scan PET scan
Correct answer is A. RATIONALE: It is important to evaluate the extent of the lesion appropriately. MRI provides the most complete anatomic information.
38.
Which of the following statements about the profile of a 20-MeV electron beam is true? A. The 20% and 50% isodose lines laterally constrict, whereas the 80% and 90% isodose lines bulge out near the field edge. B. The 20% and 50% isodose lines bulge out near the field edge, whereas the 80% and 90% isodose lines laterally constrict. C. All isodose lines demonstrate a lateral constriction near the field edge. D. All isodose lines bulge out near the field edge.
Correct answer is B. RATIONALE: For high-energy electrons, the low isodose levels bulge out, whereas the high isodose levels laterally constrict. This effect is accentuated with decreasing field size. 39.
Which of the following statements about the extent of lymph node dissection in patients with gastric cancer is true? A. A D2 dissection includes a splenectomy. B. A D2 dissection did not improve survival when compared to a D1 dissection, according to a Dutch study. C. The majority of patients received a D1 dissection in the INT-0116 randomized study evaluating postoperative chemoradiation. D. Chemoradiation should not be given to patients after a D2 dissection.
Correct answer is B. RATIONALE: A splenectomy is associated with higher complications. The Dutch study did not show a survival benefit when comparing D1 vs. D2 dissections. The majority of patients in the INT-0116 study had a D0 dissection. One large study from Korea suggests a 5% overall survival benefit with chemoradiation, even with a D2 dissection. REFERENCE: Journal of Clinical Oncology (JCO) 22:2069-2077. International Journal of Radiation Oncology, Biology, Physics (Int. J. Radiation Oncology Biol. Phys.). 2005;63(5):1279– 1285. 40.
Which of the following types of mutation presents the LEAST genetic risk to the first-generation offspring of parents who were irradiated? A. B. C. D.
Autosomal-recessive Autosomal-dominant Mitochondrial Y-linked
Correct answer is A. RATIONALE: Since a recessive mutation must be inherited from both parents, the chances of such an induced mutation affecting the first generation of offspring would be exceedingly small.
41.
Which of the following treatment plans is best for a patient with stage T1 squamous cell carcinoma of the glottic larynx? A. B. C. D.
79.2 Gy in 66 fractions of 1.2 Gy administered twice daily 63 Gy in 28 fractions of 2.25 Gy 63 Gy in 35 fractions of 1.8 Gy 60 Gy in 30 fractions of 2.0 Gy, plus cisplatin
Correct answer is B. RATIONALE: Choice B is the current "gold standard." Choice A has been shown to be inferior. Choice C is acceptable for stage T2, but not stage T1. Choice D is much too aggressive. 42.
What is the most common subtype of classical Hodgkin lymphoma? A. B. C. D.
Large B-cell Mixed cellularity Nodular sclerosing Lymphocyte depleted
Correct answer is C. RATIONALE: Nodular-sclerosing Hodgkin lymphoma is the most common subtype of classic Hodgkin lymphoma, accounting for more than two thirds of all cases. Mixed-cellularity Hodgkin lymphoma is the next most common subtype at 30%, followed by lymphocyte-rich and lymphocyte-depleted Hodgkin lymphoma. 43.
The null hypothesis that the hazard ratio equals 1 can be tested using which of the following regression analysis methods? A. B. C. D.
Cox Logistic Polynomial Multiple linear
Correct answer is A. RATIONALE: Cox regression models are focused on hazard ratios, whereas the other regression model options provide information about odds ratios or mean values.
44.
Which of the following radiobiological processes explains the increased radiosensitivity of exponentially growing HeLa cells in culture as the dose rate is lowered from 154 to 37 cGy/h? A. B. C. D.
The cells become less hypoxic. The cells repair DNA damage more efficiently. The cells redistribute into the G2 phase of the cell cycle. The chromatin becomes more condensed, enhancing DNA damage.
Correct answer is C. RATIONALE: The inverse dose rate effect is manifest as an increase in cell killing with decreasing dose rate (of low-LET radiation), the opposite of what would otherwise be expected (i.e., a decrease in cell killing with decreasing dose rate). This phenomenon has been observed when exponentially growing cells in culture are irradiated with a series of decreasing dose rates. There appears to be a cell line-specific, “critical” dose rate at which the change from decreasing radiosensitivity to increasing radiosensitivity occurs. The inverse dose rate occurs because, at or near the critical dose rate, further cell division is inhibited and instead, cells begin to accumulate at the G2 phase cell cycle checkpoint. Because G2 phase cells are more radiosensitive that G1 and S phases cells, this cell cycle redistribution effect results in a net sensitization of the population as a whole. REFERENCE: Hall and Giaccia. Radiobiology for the Radiologist. 6th edition, Chapter 5. 45.
The internal target volume (ITV) is defined as the: A. B. C. D.
gross tumor volume plus a margin for microscopic growth. clinical target volume plus a margin for internal motion. planning target volume plus a margin for setup error. organ at risk volume plus a margin for setup error and internal motion.
Correct answer is B. RATIONALE: ICRU 50 and 62 have established the definitions for a series of volumes that are used in radiation therapy. Option A is the clinical target volume (CTV), and option D is the planning organ at risk volume (PRV). The ITV is defined by option B. 46.
The most common cancer in the renal pelvis is: A. B. C. D.
transitional cell carcinoma. squamous cell carcinoma. clear cell carcinoma. adenocarcinoma.
Correct answer is A. RATIONALE: Most (90%) upper urinary tract (including renal pelvis) tumors are transitional cell in origin. 47.
Which of the following tests would most reliably confirm the cause of MRI enhancement in the treatment field 6 months after a patient with glioblastoma has completed chemoradiation? A. 18FDG PET scan B. MR spectroscopy C. Diffusion-weighted MRI D. Biopsy
Correct answer is D. RATIONALE: Although all of the tests may suggest tumor progression versus treatment effect, none replace a stereotactic or open biopsy.
48.
Which of the following sites should be included in radiation therapy for a stage T3 squamous cell carcinoma of the hypopharynx? A. B. C. D.
Superior retropharyngeal lymph node (Rouvière node) Pterygomandibular raphe Level VI lymph nodes Meckel's cave
Correct answer is A. RATIONALE: Carcinomas of the hypopharynx drain into the retropharyngeal nodes, and they should be covered to the base of the skull. Meckel's cave should be covered when treating cancer with perineural invasion of the trigeminal nerve. 49.
What is the cumulative incidence of secondary cancers in patients who receive EBRT for hereditary retinoblastoma? A. B. C. D.
00% to 5% 10% to 15% 35% to 40% 70% to 75%
Correct answer is C. RATIONALE: Patients with hereditary retinoblastoma who received external-beam radiation therapy (EBRT) have a 35% cumulative incidence of secondary cancers. A child with unilateral retinoblastoma who presents with advanced intraocular disease and undergoes enucleation has a cure rate of >95%. REFERENCE: Chintagumpala, et al. The Oncologist. October 2007;12(10):1237-1246. 50.
A 5-year-old boy who has pure germinoma with normal blood and CSF β−hCG and α−fetoprotein levels has a complete response to subtotal resection and four cycles of systemic chemotherapy. Which of the following treatment recommendations would be most appropriate? A. B. C. D.
Craniospinal radiation therapy with a boost dose to the primary site Local radiation therapy Whole-brain radiation therapy Stereotactic radiosurgery
Correct answer is B. RATIONALE: Local radiation therapy is recommended for a 5-year-old patient who has had a good response to chemotherapy. The appropriate radiation treatment in patients with CNS germ cell tumors has evolved from craniospinal radiation therapy to local fields in the era of chemotherapy. Withholding radiation therapy is associated with an unacceptable risk of recurrence. 51.
Homologous recombination involves repair of which of the following DNA lesions? A. B. C. D.
Base damage Single-strand breaks Double-strand breaks DNA-protein crosslinks
Correct answer is C. RATIONALE: Homologous recombination (HR) and nonhomologous endjoining (NHEJ) are involved in DNA double-strand break repair, with each type predominating in different parts of the cell cycle. (NHEJ in G1 phase; HR in S/G2 phases.) REFERENCE: Hall and Giaccia. Radiobiology for the Radiologist. 6th edition, Chapter 5.
52.
Disregarding the activity excreted via the urine, what is the approximate activity of 555 MBq (15 mCi) of 18FDG (T1/2 = 110 minutes) 5.5 hours after administration to a patient who is to undergo PET imaging? A. B. C. D.
017.3 MBq (0.47 mCi) 034.7 MBq (0.94 mCi) 069.4 MBq (1.88 mCi) 138.8 MBq (3.75 mCi)
Correct answer is C. RATIONALE: This item requires knowledge that T1/2 represents a decay of one half of the original activity: 5.5 h (330 m) is 3 half-lives (e.g., 0.5 x 0.5 x 0.5 = 0.125; hence, 555 MBq x 0.125 = 69.4 MBq). 53.
What is the expected progression-free survival rate after hypofractionated stereotactic body radiation therapy (SBRT) for stage IA NSCLC? A. B. C. D.
30% 50% 70% 90%
Correct answer is D. RATIONALE: Several studies, some of which were prospective (nonrandomized), have shown the local control rate to be 90% or higher for stage IA NSCLC treated with hypofractionated SBRT. REFERENCE: Fowler JF, Tome WA, Welsh JS. Estimation of the required doses in stereotactic body radiation therapy. Kavanagh BD and Timmerman RD, eds. Stereotactic Body Radiation Therapy. Lippincott, Williams & Wilkins; 2005. 54.
What percent of children with acute lymphoblastic leukemia have CNS involvement at diagnosis? A. B. C. D.
01% to 2% 03% to 5% 07% to 10% 12% to 15%
Correct answer: ABCD. RATIONALE: CNS leukemia is present at diagnosis in 3% to 5% of children with acute lymphoblastic leukemia (ALL). REFERENCE: Pediatric Radiation Oncology. 3rd edition. Lippincott, Williams & Wilkins. 55.
A whole-organ x-ray dose of 8 Gy delivered in 2-Gy fractions is most likely to cause permanent dysfunction in the: A. B. C. D.
liver. brain. spinal cord. testes.
Correct answer is D. RATIONALE: A total dose of 6 to 8 Gy will cause permanent azoospermia in almost all males. That same dose would cause little or no toxicity in the other organs listed. REFERENCE: Mettler and Upton. Medical Effects of Ionizing Radiation. 3rd edition, Chapter 1 (Table 1-8) and Chapter 6.
56.
What is the maximum dose to an organ located 2 cm outside of a 6-MV treatment field relative to the central axis dose at the same depth? A. B. C. D.
00.2% 02.0% 10% 15%
Correct answer is B. RATIONALE: Within 2 cm from the edge of the field, internal scatter contributes dose outside of the field, though the values are still fairly low. 57.
Which of the following radiation therapy methods for dose escalation has NOT been tested in a randomized phase III trial for treatment of malignant glioma? A. B. C. D.
Radiosurgery Brachytherapy Fast neutron Proton
Correct answer is D. RATIONALE: Proton radiation therapy for dose escalation has not been tested in a randomized trial. Multi-institutional randomized trials have been performed for radiosurgery, brachytherapy, and fast neutrons without showing a survival benefit. 58.
What is the mechanism of action of irinotecan? A. B. C. D.
Topoisomerase I inhibition Topoisomerase II inhibition DNA binding and intercalation DNA crosslinking
Correct answer is A. RATIONALE: Irinotecan is a camptothecin analogue that functions as a topoisomerase-I inhibitor. Irinotecan is used to treat numerous malignancies, including colorectal cancer and lung cancer, and is being investigated to treat other diseases, both alone and in combination with other agents. REFERENCE: CPT-11. Camptosar. Pfizer Inc; New York, NY (PACKAGE INSERT). 59.
Which of the following statements about brain metastases secondary to breast cancer is true? A. The overall incidence is 15%. B. The most common symptoms are acute onset of headaches, nausea, and vomiting. C. Lung, liver, or lymph node metastases predict a higher risk for development of brain metastases. D. Age does not affect the risk for development of brain metastases.
Correct answer is C. RATIONALE: The incidence of brain metastases is 5%. The most common finding associated with the onset of brain metastases is a slowly progressive neurological deficit. Seizures and acute stroke or TIA-like symptoms also can be seen. A higher risk of brain metastases is seen in patients who are under 40 years of age; have HER-2-positive disease; and have ER-negative disease. REFERENCE: Kaal ECA and Vecht C. CNS complications of breast cancer: current and emerging treatment options. CNS Drugs. 2007;21(7):559-579.
60.
Which of the following chromosomal translocations is most commonly associated with chronic myelogenous leukemia (CML)? A. B. C. D.
t(8;21) t(9;22) t(12;15) t(15;17)
Correct answer is B. RATIONALE: It is important to recognize the proper diagnosis of chronic myelogenous leukemia (CML). The relationship of CML to chromosomal translocation t(9;22) is well documented. 61.
Overexpression of p16 in HPV-associated oropharyngeal squamous cell carcinoma is an independent prognostic factor for: A. B. C. D.
lower disease-free survival. higher overall survival. higher local recurrence. higher response rate to EGFR-targeted therapy.
Correct answer is B. RATIONALE: In patients with oropharyngeal squamous cell carcinoma, overexpression of p16 (a subtype of HPV) has been shown to be an independent prognostic factor for local recurrence, disease-free survival, and overall survival. REFERENCE: Weinberger, et al. Clinical Cancer Research. September 1, 2004;10:5684-5691. 62.
Plateau-phase cells in culture received 4-Gy x-ray irradiation and then were exposed to either saline alone (control) or saline plus a nontoxic new drug for 2 hours postirradiation before being subcultured and assayed for clonogenic survival. Which of the following would explain the observation of a higher surviving fraction in the control cells than in the drug-treated cells at the end of the experiment? A. B. C. D.
Fixation of PLD in the drug-treated cells Fixation of SLD in the drug-treated cells Fixation of PLD in the control cells Fixation of SLD in the control cells
Correct answer is A. RATIONALE: Any postirradiation treatment that has the net effect of reducing plateau phase cell survival (in the absence of any other direct toxicity) is said to have “fixed” (i.e., made permanent) potentially lethal radiation damage. Based on the operational definitions of both sublethal damage (SLD) and potentially lethal damage (PLD), SLD and its repair cannot be demonstrated unless at least two radiation doses are given with a radiationfree interval between them. REFERENCE: Hall and Giaccia. Radiobiology for the Radiologist. 6th edition, Chapter 5.
63.
According to the NRC, personnel dosimeters are required for: A. staff members of a department who use radiation-producing devices. B. staff members of a department who could be in rooms with radiation-producing devices. C. radiation workers likely to receive a whole-body dose in excess of 5 mSv/year. D. radiation workers likely to receive a whole-body dose in excess of 50 mSv/year.
Correct answer is C. RATIONALE: According to 10 CFR 20.1502, personnel monitoring are required for all employees likely to receive a dose in excess of 10% of the annual NRC limit (50 mSv to the whole body). 64.
Which of the following treatments would be most appropriate for an 8-year-old boy with nondisseminated unifocal pure germinoma of the pineal area? A. B. C. D.
Four cycles of etoposide and cisplatin alone Radiation therapy to the primary tumor alone Whole-ventricular radiation therapy, followed by a boost dose to the primary tumor Complete surgical resection, followed by radiation therapy to the primary tumor
Correct answer is C. RATIONALE: Involved-field radiation therapy alone is regarded as inadequate therapy for focal CNS germinoma with or without complete surgical resection. Omission of consolidative radiation therapy (RT) after chemotherapy will result in a high risk of disease recurrence. Although the treatment volume for focal CNS germinoma has been vigorously debated, a recent systematic review from Lancet Oncology (2005) by Rogers, et al. showed that whole-brain or whole-ventricular RT followed by a boost yielded identical rates of local control, neuraxis control, and survival compared to craniospinal RT followed by a boost in adequately staged patients. REFERENCE: Rogers SJ, Mosleh-Shirazi MA, and Saran FH. Radiotherapy of localized intracranial germinoma: time to sever historical ties? Lancet Oncology. 2005;6(7):509-519. 65.
A false-positive occurs when test results are: A. B. C. D.
positive for the presence of disease but no disease is present. negative for the presence of disease but the disease is present. positive for the presence of disease and the disease is present. negative for the presence of disease and no disease is present.
Correct answer is A. RATIONALE: False-positive results occur when the results are positive for the presence of disease, but the patient does not have the disease.
66.
Which of the following statements about patients who have breast cancer with ipsilateral supraclavicular metastases and no other more distant disease at diagnosis is true? A. B. C. D.
The AJCC stage is IIIB. They are not eligible for breast-conserving therapy. The radiation dose to the supraclavicular lymph nodes is 50 to 66 Gy. The supraclavicular fossa is managed by neoadjuvant chemotherapy, supraclavicular lymph node dissection, and radiation therapy.
Correct answer is C. RATIONALE: The AJCC stage for ipsilateral supraclavicular lymph nodes is IIIC. The study did not exclude patients from breast conservation, gave 50 to 66 Gy (median 58 Gy) to the supraclavicular fossa, and did not perform supraclavicular dissections. REFERENCES: AJCC Cancer Staging Manual, 6th edition. Huang, et al. International Journal of Radiation Oncology, Biology, Physics (Int J Radiat Oncol Biol Phys). 2007;67:490-6. 67.
Bleomycin is more toxic to oxygenated cells than to hypoxic cells due to: A. B. C. D.
rapid proliferation of the oxygenated cells. poor penetration of the drug into hypoxic cells. increased repair of drug damage in hypoxic cells. increased damage fixation in the presence of oxygen.
Correct answer is D. RATIONALE: Bleomycin has a unique mechanism of action different from many other chemotherapy agents, and one that makes the drug more "radiation-like." The bleomycin molecule contains a group of five nitrogen atoms arranged in a square-pyramidal conformation that binds divalent iron as the active ligand. Molecular oxygen, bound by the iron, produces highly reactive, highly localized hydroxyl radicals that cause DNA damage (not unlike a radiation-induced locally multiply damaged site or LMDS). Because of this, bleomycin is more toxic to aerobic cells than to hypoxic ones. REFERENCE: Pratt, Ruddon, Ensminger, and Maybaum. Chapter 7: Noncovalent DNA-binding drugs. The Anticancer Drugs. 2nd edition. 1994. 68.
Which of the following characteristics is associated with the majority of patients who have follicular lymphoma? A. B. C. D.
It predominantly affects young adults. The Bcl-2 gene rearrangement is typically present. Bone marrow involvement is uncommon. Without therapy, the median survival of patients is less than 5 years.
Correct answer is B. RATIONALE: The majority of patients with follicular lymphoma present with widespread disease and bone marrow involvement. The disease most commonly affects elderly patients. Due to its very indolent nature, even with observation, the median survival of these patients exceeds 5 years. The t(14;18) and Bcl-2 gene rearrangement is present in the majority of patients with follicular lymphoma.
69.
An accelerating waveguide in a megavoltage linear accelerator is typically made of: A. B. C. D.
aluminum. copper. plastic. acrylic.
Correct answer is B. RATIONALE: An accelerating waveguide in a megavoltage linear accelerator is typically made of a material that is a good conductor. 70.
Which of the following factors is associated with the highest risk for the development of breast cancer? A. B. C. D.
Estrogen replacement therapy Estrogen and progestin replacement therapy Age of greater than 40 years Postmenopausal obesity
Correct answer is C. RATIONALE: Age is the strongest risk factor for the development of breast cancer. Breast cancer is rarely seen before 20 years of age and rises sharply between 40 and 80 years of age. REFERENCE: Harris, Lippmann, Morrow, and Osborne. Diseases of the Breast. 4th edition. 2004;223-276. 71.
The administration of concurrent cisplatin-based chemotherapy with radiation therapy for head and neck cancer has been shown to decrease: A. B. C. D.
distant metastases. locoregional recurrence. acute toxicity. late toxicity.
Correct answer is B. RATIONALE: All trials supporting chemoradiotherapy show an improvement in locoregional control. Very few also show an effect on distant disease. Toxicity is greater with concurrent chemotherapy and radiation therapy, and there is no logic to decreasing the dose of radiation therapy since it is the most effective "drug" we have. 72.
Which of the following sets of unfavorable prognostic criteria is used by the EORTC for patients with early-stage Hodgkin lymphoma? A. "B" symptoms, age, pathology, extranodal sites, and number of involved sites B. "B" symptoms, age, erythrocyte sedimentation rate (ESR), mediastinal bulk, and number of involved sites C. "B" symptoms, pathology, ESR, mediastinal bulk, and number of lymph node sites D. Gender, ESR, mediastinal bulk, number of sites, and extranodal sites
Correct answer is B. RATIONALE: The EORTC used the following criteria for assigning patients with early-stage Hodgkin lymphoma to the favorable vs. unfavorable prognostic group: "B" symptoms, age, erythrocyte sedimentation rate (ESR), mediastinal bulk, and the number of nodal sites.
73.
Which of the following is a kinase responsible for phosphorylating downstream proteins in response to DNA damage? A. B. C. D.
BRCA1 BRCA2 p53 ATM
Correct answer is D. RATIONALE: Although ATM, BRCA1, BRCA2, and p53 are all important proteins that participate in the DNA damage response after irradiation, ATM is the only one that also has kinase activity essential for the phosphorylation of downstream proteins. ATM contains a highly conserved C-terminal kinase domain related to phosphatidylinositol 3-kinase (PI-3K). REFERENCE: Tannock, Hill, Bristow, and Harrington. The Basic Science of Oncology. 4th edition, Chapter 5. 74.
A magnetron in a megavoltage linear accelerator is used to: A. B. C. D.
steer the electron beam. stabilize the electron bunch current. transfer heat from the waveguide. produce microwave power.
Correct answer is D. RATIONALE: A magnetron is a microwave power source used in megavoltage linear accelerator, radar, and microwave ovens. 75.
Which of the following statements about the diagnosis and treatment of gynecomastia related to the use of antiandrogen therapy for prostate cancer is true? A. The rate of gynecomastia in the Scandinavian SPCG-7/SFUO trial was 30% for patients given prophylactic breast irradiation. B. Gynecomastia is associated with diffuse enlargement of the breast. C. Gynecomastia is associated with a mass adjacent to the nipple. D. The radiation treatment schedule should be 20 Gy (2 Gy x 10 fractions).
Correct answer: ABCD. RATIONALE: The rate of gynecomastia was 30% for patients given prophylactic breast irradiation vs. 70% rate in the control group. Option B/C: Gynecomastia is associated with a firm, rubbery mass immediately deep to the nipple – areolar complex. An adjacent mass is worrisome for breast cancer and should be evaluated with mammography/ultrasound. Diffuse breast enlargement is pseudogynecomastia. Option D: There are variable fractions, but this schedule is protracted and not typical of what is used. A common treatment schedule is 3 Gy/fraction x 4–5 fractions. REFERENCES: Gikas P, Mokbel K. Management of gynecomastia: an update. International Journal of Clinical Practice. 2007;61(7):1209-1215. Gunderson & Tepper, eds. Clinical Radiation Oncology. 2nd edition. 2007;1561.
76.
Which of the following outcomes was demonstrated in the INT-0123 (Minsky) study comparing the use of 50.4 and 64.8 Gy of radiation therapy with chemotherapy for esophageal cancer? A. High-dose radiation therapy resulted in a significant survival benefit in the as-treated analysis, but outcomes were not improved in the high-dose group by intent-to-treat. B. The benefit of high-dose radiation therapy was obscured due to patient deaths before a total dose of 50.4 Gy was reached. C. There was no suggestion of a survival benefit with high-dose radiation therapy either in intent-to-treat or as-treated analysis. D. Local control was significantly better in the high-dose radiation therapy arm.
Correct answer is C. RATIONALE: In the report of INT-0123, an as-treated analysis was performed due to the high incidence of early grade 5 toxicity in the high-dose radiation therapy arm. However, there remained no survival difference in the two arms. Local failure was not significantly different. 77.
According to a recently published (Slotman) randomized trial, PCI improves survival in patients who have SCLC with: A. B. C. D.
limited-stage disease irrespective of response to chemotherapy. extensive-stage disease irrespective of response to chemotherapy. limited-stage disease with no progression during chemotherapy. extensive-stage disease with no progression during chemotherapy.
Correct answer is D. RATIONALE: Based on the PCI meta-analysis, patients who had limitedstage SCLC and achieved a complete response to chemotherapy experienced improved survival rates with PCI. In the European randomized trial (Slotman, et al), patients who had extensive-stage small cell lung cancer and achieved any response to chemotherapy were eligible and experienced improved survival rates. 78.
Which of the following statements about the therapeutic ratio in patients receiving curative radiation therapy for cancer is true? A. For approximately the same total dose, shortening the overall treatment time increases the chances of local tumor control without increasing acute side effects. B. The goal of curative radiation therapy is to achieve a complete tumor response by the last day of treatment while minimizing acute side effects. C. The goal of curative radiation therapy is to kill all clonogenic tumor cells that could give rise to a recurrence while minimizing the risk for serious complications. D. The risk of serious late complications should be limited to 10% or less 5 years after treatment.
Correct answer is C. RATIONALE: The goal of curative radiation therapy is to inactivate all clonogenic tumor cells that could give rise to a recurrence while simultaneously minimizing the risk for serious late normal tissue complications. Shortening the overall treatment time may increase the chance of local tumor control in some cases (i.e., especially for tumors containing a subset of rapidly growing cells), but it runs the risk of exacerbating acute normal tissue reactions as well. Achieving a complete tumor response – reduction of tumor burden to below the limits of clinical detection – by the last day of radiation therapy is a desirable goal, but it in no way guarantees that all clonogenic tumor cells have been eradicated. Typically, the risk of serious late complications should be limited to 5% or less (not 10%) 5 years after treatment.
79.
What is an advantage of using a "field in a field" treatment technique for breast treatment versus using a wedge? A. B. C. D.
Avoids the need for a skin bolus Avoids the need for collimator rotation for field matching with a supraclavicular field Decreases the dose to the contralateral breast Decreases the magnitude of the hot spot
Correct answer is C. RATIONALE: The addition of a wedge, especially when added to the medial treatment field, will increase the dose to the contralateral breast due to an increase in scatter radiation. By using a "field in a field" technique, this increase in scatter dose may be avoided. 80.
A patient with Hodgkin lymphoma has a 12-cm anterior mediastinal mass with bilateral involvement of the hilar lymph nodes and invasion of the anterior chest wall detected on CT scan. No disease is found below the diaphragm, and the patient has no "B" symptoms. Which of the following stages is associated with this patient's disease? A. B. C. D.
IAEX IIAEX IIIAEX IVAEX
Correct answer is B. RATIONALE: Involvement of two lymph node regions (both hilum) on the same side of the diaphragm with localized contiguous involvement of a single extranodal site (chest wall), with >10-cm mass, and absence of "B" symptoms constitute stage IIAEX disease. 81.
What is the AJCC stage for a patient with a tumor invading into, but not through, the muscularis propria with four positive lymph nodes after preoperative chemoradiation followed by resection? A. B. C. D.
pT2N2 pT3N2 ypT2N2 ypT3N2
Correct answer is C. RATIONALE: The "y" prefix in staging criteria is used for patients undergoing pretreatment. A tumor invading into but not through muscularis propria is classified as stage T2. Four or more lymph nodes would be classified as stage N2.
82.
Based on the updated results of the phase III (D'Amico) trial, which of the following outcomes was demonstrated in patients who had localized, unfavorable-risk prostate cancer and received radiation therapy with or without androgen deprivation? A. With longer follow-up of patients, there was a loss of significance in overall survival with the addition of androgen deprivation. B. Based on multivariate analysis, the duration of androgen deprivation had no impact on overall survival. C. Only patients with a low comorbidity score realized a benefit from androgen deprivation. D. Cardiac events were not a common cause of death in patients treated with androgen deprivation.
Correct answer is C. RATIONALE: This important update from this phase III trial helps to individualize the use of androgen deprivation for unfavorable-risk patients with prostate cancer. Comorbidity plays an important role in patients who receive androgen deprivation for prostate cancer. REFERENCE: D'Amico, et al. Journal of American Medical Association (JAMA). 2008;23:289-295. 83.
Which of the following statements about the management of DCIS is true? A. In the NSABP B24 trial, the addition of tamoxifen to irradiation of the breast decreased the rate of IBTR. B. In the NSABP B24 trial, the addition of tamoxifen to radiation therapy did not affect the rate of invasive breast cancer recurrence. C. Margin status predicts the risk for noninvasive IBTR but does not predict the risk for invasive IBTR. D. The addition of tamoxifen to radiation therapy results in a greater reduction of IBTR in postmenopausal women than in premenopausal women.
Correct answer is A. RATIONALE: The addition of tamoxifen reduced the IBTR of all recurrences from 11% to 7.7%. Tamoxifen reduced the rate of invasive cancer from 5.3% to 2.6%. It did not affect the rate of noninvasive recurrence (5.8% with radiation therapy alone vs. 5.0% with radiation therapy and tamoxifen). Margin status predicts the risk for IBTR, regardless of whether the recurrence has an invasive or a noninvasive histology. Premenopausal women experience a greater benefit from tamoxifen and radiation therapy than postmenopausal women because premenopausal women have higher rates of IBTR overall. REFERENCE: Harris, Lippman, Morrow, and Osborne. Diseases of the Breast. 4th edition. 2004;521-537. Halpern, Perez, and Brady. Principles and Practice of Radiation Oncology. 5th edition. 2008;1162-1174. 84.
Which of the following factors is most important in determining the prognosis of patients with intracranial ependymoma? A. B. C. D.
Sex of the patient Extent of resection Location of the tumor Use of chemotherapy
Correct answer is B. RATIONALE: Among the factors listed above, the extent of resection is the most important prognostic factor. The use of chemotherapy has not been consistently shown to impact survival or tumor control. REFERENCE: Merchant TE. Current management of childhood ependymoma. Oncology. Williston Park; May 2002;16(5):629-42, 644.
85.
A tumor consisting of 109 cells is characterized by a survival curve with α = 0.3 Gy 1 and − β = 0.015 Gy 2. If the tumor is treated with repeated, once-daily 2-Gy fractions, which of the following total doses will yield a 90% tumor control probability? −
A. B. C. D.
50 Gy 60 Gy 70 Gy 80 Gy
Correct answer is C. RATIONALE: This item incorporates knowledge of both of the following cell survival models, the multi-fraction survival response and Poisson statistics. With a starting population of 109 tumor cells (all assumed to be clonogenic in this example), a TCD90 (90% tumor control probability) would correspond to that total radiation dose that reduces the initial population to an average of 10-1 cells or 10 logs of cell killing (SF = 10-10). Because a multifraction survival curve is roughly exponential, the following relatively simple calculations are possible: α β 2 1) SF2 (the surviving fraction after the single dose of 2 Gy) = e–( D+ D ) = e–[(0.3x2) + (0.015x4)] = e–0.66 ≈ 0.52 2) Then: Final SF = (SF2)N, where N = number of fractions Final SF = 10-10 = (0.52)N Taking the natural log of both sides of the equation and solving for N: N ≈ 35 fractions – of 2 Gy each – corresponding to a total dose of 70 Gy. 86.
Which of the following constitutes a serious error (potentially 20% or greater) in treatment delivery to a point within an irradiated volume? A. B. C. D.
Incorrect wedge angle (45° versus 15°) Incorrect wedge direction for a 45° wedge Incorrect photon energy (6 instead of 18 MV) when prescribed to a 10 cm depth SAD treatment using SSD monitor units for an 11 cm depth calculation
Correct answer is B. RATIONALE: The dose difference in the use of a 45° wedge vs. a 15° wedge is approximately 30%. An incorrect energy represents a difference of ~1.5% per cm, and SAD vs. SSD depends on inverse square (2% per cm). An incorrect wedge angle would flip the 'toe' hot spot with 'heel' cold spot, leading to a potentially worst-case dose change of ~70%. 87.
Which of the following types of benign meningioma should NOT be treated with stereotactic radiosurgery? A. B. C. D.
Optic nerve sheath Skull base Convexity Parasagittal
Correct answer is A. RATIONALE: Radiosurgery should not be performed for optic nerve sheath tumors given the risk for optic neuropathy.
88.
Which of the following clinical descriptions is associated with grade III heterotrophic bone formation? A. B. C. D.
Bony islands within the soft tissues around the hip Bony ankylosis between the proximal femur and pelvis Exophytes of the pelvis or proximal femur and a distance of at least 1 cm or more Exophytes of the pelvis or proximal femur and a distance of less than 1 cm
Correct answer is D. RATIONALE: Option A: Grade II. Option B: Grade IV. Option C: Grade II. Option D: Grade III. REFERENCES: Booker AF, Bowerman JW, Robinson RA, Riley CH: Ectopic ossification following total hip replacement. Journal of Bone Joint Surgery. 1973;55:1629-1632. Gunderson & Tepper, eds. Clinical Radiation Oncology. 2nd edition. 2007;1561-1562. 89.
Which of the following statements about the use of radioactive iodine for patients with thyroid malignancies is true? A. Iodine imaging should be performed before ablation of the thyroid remnant after surgery. B. Typically, iodine imaging should be performed within 1 month after CT scans with IV contrast. C. A high level of thyroxin is necessary before iodine imaging. D. The typical dose of radioactive iodine therapy is between 50 and 100 mCi.
Correct answer is A. RATIONALE: It is important to understand how and when to use iodine imaging. Prior to iodine imaging, a high level of TSH is necessary for an optimal uptake of radiolabeled iodine. 90.
What is the probability that solitary plasmacytoma of the bone will progress to multiple myeloma within 10 years? A. B. C. D.
10% to 20% 30% to 40% 60% to 70% 80% to 90%
Correct answer is C. RATIONALE: It is important to know this fact for counseling patients. The majority of patients will progress to multiple myeloma, and surveillance/follow-up is important after primary therapy.
91.
What is the purpose of randomization using a probability model in a clinical trial? A. B. C. D.
Identify unknown prognostic factors Select a representative sample of patients with the disease of interest Provide an unbiased estimate of the treatment effect in each arm of the study Assign equal numbers of patients to each arm of the study
Correct answer is C. RATIONALE: A random sample helps to provide a fair, unbiased comparison of the treatments within the population of patients from which participants are recruited, although this population may not be representative of all patients with the disease. Randomization may not result in equal, or nearly equal, numbers of patients with a particular characteristic in each treatment group. It does distribute biasing characteristics according to a known probability distribution so that they do not obscure identification of treatment effects, if any, by statistical tests. The number of patients in each study arm may differ, either by design or as a product of the recruitment process. 92.
Which of the following components of a signaling network help to prevent genomic instability and carcinogenesis? A. B. C. D.
Executioners Promoters Initiators Sensors
Correct answer is D. RATIONALE: Optimal DNA damage responses are regulated by sensors, transducers, and effectors. Sensors, typically chromatin-bound proteins, can detect DNA damage and recruit signal transducers. Transducers are protein kinases that can amplify the signal by phosphorylation of numerous downstream proteins. Effectors are the proteins modified by phosphorylation that can negatively regulate the cell cycle progression. 93.
According to the NCI Canada randomized trial, which of the following statements about the use of preoperative versus postoperative radiation therapy for patients with sarcoma of the extremities is true? A. B. C. D.
Field sizes were significantly larger. It resulted in a higher incidence of postoperative wound complications. It increased the incidence of late fibrosis. It improved local control.
Correct answer is B. RATIONALE: The NCI Canada study was terminated after interim analysis showed a higher rate of wound complications in the preoperative radiation therapy (RT) arm. The preoperative arm also used smaller fields sizes. This is expected since the full operative bed/scars do not have to be included in the preoperative setting. The updated report of this trial demonstrated a trend towards less late fibrosis with preoperative RT compared to postoperative RT. No local control difference was seen between the two arms of the study. REFERENCES: O'Sullivan, et al. Lancet. 2002. Davis, et al. Radiotherapy & Oncology. 2005.
94.
The most important prognostic factor for patients with inflammatory breast cancer is: A. B. C. D.
tumor response to chemotherapy. presence or absence of dermal lymphatic invasion. HER-2/neu amplification. patient age.
Correct answer is A. RATIONALE: Many studies have confirmed that a pathologic complete response to chemotherapy is the most important prognostic factor in inflammatory breast cancer. Dermal lymphatic invasion and HER-2/neu positivity may or may not be associated with inflammatory breast cancer but have not been reported to be more important than response to chemotherapy. REFERENCE: Harris, et al. International Journal of Radiation Oncology, Biology, Physics (Int J Radiat Oncol Biol Phys). 2003;55:1200-8. 95.
According to current U.S. regulatory standards, which of the following radiation dose units is most appropriately used to express the dose limit for individual members of the public? A. B. C. D.
Exposure (in Roentgen) Equivalent dose (in Gray) Effective dose (in Sievert) Total effective dose equivalent (in Sievert)
Correct answer is D. RATIONALE: Total effective dose equivalent, in Sievert, is the current term. Residents need to know that older generic terms (dose, exposure, etc.) no longer apply to regulatory standards. Moreover, it requires knowledge that Sievert is the unit for regulatory standards. 96.
What is the most common histologic subtype of cholangiocarcinoma? A. B. C. D.
Adenocarcinoma Neuroendocrine carcinoma Transitional cell carcinoma Squamous cell carcinoma
Correct answer is A. RATIONALE: More than 90% of cholangiocarcinomas are adenocarcinomas. 97.
Which of the following treatments should be performed for patients with bilateral Wilms tumor? A. B. C. D.
Bilateral renal biopsy, followed by preoperative chemotherapy Bilateral renal biopsy, followed by immediate radiation therapy and chemotherapy Bilateral nephrectomy and consideration for kidney transplant Nephrectomy of the worse side, followed by chemotherapy and radiation therapy
Correct answer is A. RATIONALE: The goal in patients with bilateral Wilms tumor is to obtain local control while sparing renal parenchyma. Therefore, upfront cytoreduction with chemotherapy is usually offered before a second-look surgery. The 10-year overall survival for patients with synchronous tumors is 70%, according to NWTS-2 and -3 and SIOP 1, 2, and 5 studies. Bilateral Wilms tumor is regarded as stage V disease.
98.
Low-dose-rate prostate brachytherapy as monotherapy is NOT appropriate for patients with: A. B. C. D.
stage T2a prostate cancer. a prostate volume of 40 cc. a Gleason score of 3+3. an AUA score of 20.
Correct answer is D. RATIONALE: Good candidates for prostate brachytherapy alone are lowrisk patients with stage T1-T2a disease, Gleason score of 6 or below, PSA less than 10, no enlarged prostate or high AUA score. 99.
Which of the following chromosomal translocations is most closely associated with Burkitt's lymphoma? A. B. C. D.
t(8;14) t(11;14) t(11;18) t(14;18)
Correct answer is A. RATIONALE: The (8;14) chromosomal translocation is most closely associated with Burkitt's lymphoma. The rest of the translocations are for mantle cell lymphoma (11;14), marginal cell lymphoma (11;18), and follicular cell (14;18) lymphoma. 100.
Which of the following agents is a radiation protector? A. B. C. D.
Misonidazole Amifostine Tirapazamine Iododeoxyuridine
Correct answer is B. RATIONALE: Amifostine is a "true" radiation protector that has no effect in and of itself, but in combination with radiation acts within milliseconds to scavenge radiationinduced free radicals that might otherwise interact with cellular components, especially DNA, and lead to irreparable damage. (Several other classes of agents are "apparent" radioprotectors in that they likewise afford protection of normal tissues, although by mechanisms other than rapid, free radical scavenging, e.g., a cytokine that stimulates bone marrow to increase production of new white blood cells, thereby "heading off" a potentially dangerous drop in peripheral white cell counts.) Misonidazole is a hypoxic cell radiosensitizer, tirapazamine is a bioreductive drug selectively toxic to hypoxic cells, and iododeoxyuridine is a radiosensitizer of rapidly proliferating cells.
101.
Which of the following responses of silver halide film used for quality assurance of an IMRT fluence pattern is most accurate? A. It tends to overrespond due to the lower energy of the large amount of scatter dose. B. It is highly dependent on the temperature of the solid water phantom in which it is measured. C. It will be less than the response in tissue because of the lower Z of silver. D. It will not change significantly with different processing techniques.
Correct answer is A. RATIONALE: A significant issue with film is its over-response to lowenergy x-rays due to the high atomic number of its active material, silver (Z = 47). As a result, film is much more sensitive to the interaction of low-energy photons, such as the influence of scattered photons during IMRT QA. 102.
In a prospective study comparing patients with prostate cancer treated with 3D conformal radiation therapy with or without an endorectal balloon (ERB), the ERB group had: A. B. C. D.
reduced late rectal toxicity. better biochemical outcome. more high-grade telangiectasia. increased rectal stricture.
Correct answer is A. RATIONALE: ERB reduced the rectal wall volume exposed to doses >40 Gy, resulting in reduction of late rectal mucosal changes and reduced late rectal toxicity. REFERENCE: van Lin EN, et al. Reduced late rectal mucosal changes after prostate 3D conformal radiation therapy (3D-CRT) with endorectal balloon as observed in repeated endoscopy. International Journal of Radiation Oncology, Biology, Physics (Int J Radiat Oncol Biol Phys). 2007;67(3):799-811. 103.
Which of the following factors is NOT prognostic for patients with medulloblastoma? A. B. C. D.
Stage Extent of resection Age younger than 3 years Location of tumor
Correct answer is D. RATIONALE: The specific location of the primary tumor does not appear to have prognostic implication, though tumors in the cerebellar hemisphere tend to occur in older patients. The other factors have a clear effect on prognosis.
104.
Which of the following FIGO stages is associated with ovarian carcinoma with implants confined to the pelvis and malignant cells in the peritoneal washings? A. B. C. D.
IIC IIIA IIIB IIIC
Correct answer is A. RATIONALE: FIGO stage IIC signifies pelvic extension and/or implants with malignant cells in ascites or peritoneal washings. FIGO stage IIIA = microscopic peritoneal metastasis beyond pelvis; stage IIIB = macroscopic peritoneal metastasis beyond pelvis 2 cm or less in dimension; stage IIIC = peritoneal metastasis beyond pelvis more than 2 cm in greatest dimension and/or regional lymph node metastasis. 105.
Which of the following organs is composed of anatomically defined FSUs? A. B. C. D.
Skin Heart Spinal cord Liver
Correct answer is D. RATIONALE: Withers' functional subunit model proposes that the irradiation volume dependence of normal tissue tolerance depends in part on the structural and functional organization of tissues into functional subunits (FSUs). For some organs, such as the liver or kidney, an FSU likely corresponds to the anatomically defined structure that would be minimally required to perform the function of that tissue (i.e., a liver lobule and nephron, respectively). For other organs, such as the skin, heart, central nervous system, and others, what constitutes an FSU is either unknown or not clearly defined in either an anatomic or histological sense. REFERENCE: Hall and Giaccia. Radiobiology for the Radiologist. 6th edition, Chapter 19. 106.
Extramedullary plasmacytoma is most commonly located in the: A. B. C. D.
lower extremities. head and neck. lungs. spine.
Correct answer is B. RATIONALE: It is important to know where extramedullary plasmacytoma is located in making a differential diagnosis. Extramedullary plasmacytoma may involve the nasal cavity, sinuses, nasopharynx, tonsils, and larynx. 107.
What is the approximate depth of the 90% dose for a 16-MeV electron beam? A. B. C. D.
02 cm 04 cm 08 cm 16 cm
Correct answer is B. RATIONALE: As a rule of thumb, the depth of the 90% depth dose can be approximated as E(MeV)/4.
108.
Which of the following is used to decide when a diagnostic test should be ordered? A. B. C. D.
Central limit theorem Inferential statistics Threshold model Level of significance
Correct answer is C. RATIONALE: The threshold model is used to decide when a diagnostic test should be ordered, as opposed to doing nothing or treating the patient without ordering the test. Central limit theorem states that the distribution of means is approximately normal if the sample size is large enough. Inference (statistical) is the process of drawing conclusions about a population of observations from a sample of observations. Level of significance applies to the probability of incorrectly rejecting the null hypothesis in a test of hypothesis. 109.
According to a prospective randomized (Donovan) trial, which of the following outcomes is associated with IMRT when compared to standard 2D radiation therapy for patients with early-stage breast cancer? A. B. C. D.
Palpable induration is reduced after 5 years. Cardiac events are reduced after 10 years. Pulmonary events are reduced after 5 years. Quality of life is improved at 5 years.
Correct answer is A. RATIONALE: A randomized trial comparing breast IMRT to standard 2D radiotherapy was published. Results comparing dose homogeneity, breast appearance, induration and quality of life were reported. No data on cardiac or pulmonary events was reported. REFERENCE: Donavan, et al. Radiotherapy and Oncology. 2007;254-64. 110.
Which of the following therapeutic options would be best after resection with negative surgical margins for a desmoid tumor? A. B. C. D.
Radiation therapy to 50 to 55 Gy Radiation therapy to 60 to 66 Gy Systemic chemotherapy Observation
Correct answer is D. RATIONALE: Desmoid tumors have a low recurrence rate following complete surgical resection.
111.
Which of the following statements about the epidemiology and initial presentation of penile cancer is true? A. Circumcision does not reduce the risk of penile cancer. B. Approximately 50% of palpable inguinal lymph nodes are pathologically positive at presentation. C. Clinically negative but pathologically positive inguinal lymph nodes are rare. D. Distant metastases are common at diagnosis.
Correct answer is B. RATIONALE: It is important to highlight that a palpable inguinal lymph node is not necessarily pathologically positive. Circumcision reduces the risk of penile cancer. Clinically negative but pathologically positive inguinal lymph nodes are common. Distant metastases are not common at diagnosis. 112.
Which of the following transcription factors is stabilized under hypoxic conditions? A. B. C. D.
AP-1 HIF-1α HIF-1β NFκB
Correct answer is B. RATIONALE: Hypoxia-inducible factor-1α (HIF-1α), upon stabilization in the relative absence of oxygen, trans-activates many downstream target genes that help cells adapt to the stresses associated with hypoxic conditions. In the presence of oxygen, HIF-1α becomes ubiquitinated, targeting it for degradation in the proteasome. REFERENCE: Hall and Giaccia. Radiobiology for the Radiologist. 6th edition, Chapter 6 (Figure 6.17 in particular). 113.
Which of the following statements about BRCA2 germline mutations is true? A. A similar histology of breast cancer is associated with patients who have BRCA1 or BRCA2 germline mutations. B. There is a higher risk for developing ovarian cancer in patients with a BRCA2 germline mutation than in patients with a BRCA1 germline mutation. C. Men with a BRCA2 germline mutation have a 15% to 20% risk of developing prostate cancer. D. Patients with a BRCA2 germline mutation have a 50% risk of developing breast cancer by 70 years of age.
Correct answer is C. RATIONALE: The histology of breast cancers occurring in patients with BRCA1 and BRCA2 germline mutations differs from one another and from patients who are sporadic carriers. Tumors in patients with BRCA1 germline mutations are ER-negative in up to 90% of cases. RCA2-related tumors are more frequently ER-positive than BRCA1-related tumors. Medullary cancers are seen more commonly in patients with BRCA1 mutations than in patients with either BRCA2 mutations or in controls. Tumors related to either BRCA1 or BRCA2 mutations tend to have higher grades when compared to sporadic tumors. The estimated risk for ovarian cancer in patients with BRCA1 mutations is 30% to 40%; the estimated relative risk (RR) is 18-29. The estimated risk for ovarian cancer in patients with BRCA2 mutations is 27%; the estimated RR is 16-19. The lifetime risk for developing breast cancer in patients with either BRCA1 or BRCA2 mutations is 60% to 80%. REFERENCES: Harris, Lippman, Morrow, and Osborne. Diseases of the Breast. 4th edition. 2004;283-284 (option B). Halpern, Perez, and Brady: Principals and Practice of Radiation Oncology. 5th edition. 2008;1630 (option C). Harris, Lippman, Morrow, and Osborne. Diseases of the Breast. 4th edition. 2004;283 (option D). Harris, Lippman, Morrow, and Osborne. Diseases of the Breast. 4th edition. 2004;283.
114.
Which of the following reportable errors most commonly occurs during radiation therapy? A. B. C. D.
Incorrect treatment site Miscalculated exposure time or dose Inadequate review of patient's chart Failure of treatment unit
Correct answer is B. RATIONALE: Calculation errors of exposure time or dose are almost twice as likely as the inadequate review of patient chart or error in an anatomical area to be treated and more than ten times as likely as the treatment unit mechanical failure (IAEA 2000 report). 115.
Which of the following statements about radiation therapy for urethral malignancies is true? A. B. C. D.
Preoperative radiation therapy is the standard of care. Nodal treatment field design depends on the tumor location. Concurrent chemoradiotherapy is not recommended. The entire urethra should be included in the treatment fields.
Correct answer is B. RATIONALE: Understanding basic concepts in the management of urethral malignancies is important, including patterns of drainage and the indications for combined modality therapy. Preoperative radiation therapy is not the standard of care. Combined chemoradiotherapy is recommended, especially for unresectable cases. Nodal portal treatment depends on the location of the tumor. 116.
Which of the following treatments is NOT commonly recommended for patients who have hematopoietic syndrome? A. B. C. D.
Administration of antibiotics Administration of hematopoietic colony stimulating factors Administration of transforming growth factor-β (TGF-β) Bone marrow transplantation
Correct answer is C. RATIONALE: Use of hematopoietic cytokines, bone marrow transplantation, and antibiotics are common treatments for hematopoietic syndrome. TGF-β possesses both tumor-inhibiting and tumor-promoting activities (depending on context) and is being studied as a possible therapeutic target for new drug development, but if anything, is an inhibitor of hematopoiesis, not a stimulator. REFERENCES: Goustin A, et al. Perspective in cancer research: Growth factors and cancer. Cancer Research. 1986;46:1015-1029. Shetty V, et al. Measurements of apoptosis, proliferation and three cytokines in 46 patients with myelodysplastic syndromes. Leukemia Research. 1996;20:891-900.
117.
Which of the following findings best indicates the need for an axillary boost dose after modified radical mastectomy and adjuvant chemotherapy for stage IIIA (T3N1) breast cancer? A. B. C. D.
There is microscopic extracapsular nodal extension. A single metastatic lymph node measures 2.5 cm. Twenty percent of the lymph nodes are positive. Fewer than six axillary lymph nodes are dissected.
Correct answer is D. RATIONALE: In a series, recurrence in the low-mid axilla was rare and not significantly higher for patients with a higher percentage of positive lymph nodes, larger nodal size, or extranodal extension. In contrast, an inadequate axillary dissection is a common indication for a boost dose of irradiation to the axillary lymph nodes. REFERENCE: Strom, et al. International Journal of Radiation Oncology, Biology, Physics (Int J Radiat Oncol Biol Phys). 2005;63:1508-13. 118.
Which of the following statements about the response rate to radionuclide therapy for painful metastatic bone disease is true? A. B. C. D.
The partial response rate for strontium is 50% to 60%. The complete response rate for strontium is 30% to 50%. The partial response rate for samarium is 40% to 50%. The complete response rate for samarium is 50% to 55%.
Correct answer is D. RATIONALE: Radionuclide Partial Rate Complete Rate 89 Sr 65 – 80% 10 – 30% Samarium 75 – 80% 54%
Response Duration ~6 mos. 2 – 4 ½ mos.
REFERENCE: Gunderson & Tepper, eds. Clinical Radiation Oncology. 2nd edition. 2007;448. 119.
How does GafChromic film differ from radiographic film? A. B. C. D.
It is more accurate. It is used to measure lower radiation doses. It does not require chemical processing. It has a more linear dose response.
Correct answer is C. RATIONALE: GafChromic film is self-developing and does not require any chemical processing.
120.
Which of the following statements best describes an intent-to-treat analysis? A. A randomized patient who is later found to be ineligible for the study may be disregarded at analysis. B. Patients are included in the analysis of the study arm to which they were randomized. C. Patients who withdraw from the study before completion should be analyzed separately. D. Patients who are noncompliant with treatment should be dropped from analysis.
Correct answer is B. RATIONALE: Omitting patients who withdraw without completing the study is a serious source of bias, as is dropping patients for noncompliance with treatment protocols. These may be patients for whom the treatment does not work or for whom the treatment has serious adverse consequences. There is no sound way to identify and eliminate this bias in the context of the trial, so the intention-to-treat analysis includes all consenting, randomized patients in the study arm to which they were randomized. 121.
Postoperative radiation therapy may be indicated for a patient who has what stage of NSCLC and is receiving what type of therapy? A. B. C. D.
T1N1 disease and is receiving adjuvant chemotherapy T1N1 disease and is unable to receive adjuvant chemotherapy T2N0 disease and is receiving adjuvant chemotherapy T2N0 disease and is unable to receive adjuvant chemotherapy
Correct answer is B. RATIONALE: The recently published update of the Adjuvant Navelbine International Trialist Association (ANITA) randomized trial demonstrated that postoperative radiation therapy provided a survival benefit in patients with both pN1 and pN2 NSCLC disease when these patients were unable to receive adjuvant chemotherapy. REFERENCE: International Journal of Radiation Oncology, Biology, Physics (Int J Radiat Oncol Biol Phys). 72(3):695–701. 122.
According to the CONKO (Oettle) trial, which of the following outcomes was associated with adjuvant therapy for patients with resected pancreatic cancer? A. B. C. D.
Local control was improved in patients receiving gemcitabine. Local control was improved in patients receiving radiation therapy. Disease-free survival was improved in patients receiving gemcitabine. Disease-free survival was not affected by radiation therapy.
Correct answer is C. RATIONALE: This is an important trial showing the efficacy of chemotherapy in the adjuvant setting. Local control was not substantially different. Radiation was not used in this study.
123.
Oxygen's "k-value" of approximately 0.5% corresponds to the O2 concentration at which: A. angiogenesis is stimulated. B. the HIF-1α transcription factor is stabilized. C. the radiosensitivity of the cell is halfway between that of the fully aerobic and fully hypoxic response. D. the fraction of hypoxic and aerobic cells in a tumor is approximately equal.
Correct answer is C. RATIONALE: Oxygen’s “k-value” corresponds to that concentration of oxygen that yields cellular radiosensitivity halfway between that of the fully oxic and fully hypoxic response. REFERENCE: Hall and Giaccia. Radiobiology for the Radiologist. 6th edition, Chapter 6. 124.
Which of the following types of carcinoma most commonly involves the fallopian tube? A. B. C. D.
Serous Mucinous Clear cell Metastatic
Correct answer is D. RATIONALE: The most common carcinoma that involves the fallopian tube is metastatic, generally from another site in the genital tract. 125.
Which of the following mixtures of 1 Ci of each radionuclide will have the highest activity after 5.26 years? Note: 169Yb (T1/2 = 32 days), 192Ir (T1/2 = 73.8 days), 60Co (T1/2 = 5.26 years), and 137Cs (T1/2 = 30 years) A. B. C. D.
169
Yb and 60Co Yb and 137Cs 192 Ir and 60Co 192 Ir and 137Cs 169
Correct answer is D. RATIONALE: This item requires an understanding of the concept of halflife. The mixture with the two longest-lived components (192Ir and 137Cs) will have the highest activity. 126.
Postoperative chemoradiation therapy is most likely to improve survival in patients with which of the following stages of NSCLC? A. B. C. D.
T1N1 T1N2 T2N1 T3N0
Correct answer is B. RATIONALE: A recent assessment of postoperative radiation therapy (RT) in 7,465 patients with resected stage II or III non-small cell lung cancer (NSCLC) found that postoperative RT increased survival in patients with N2 disease but not in those with N1 or N0 disease. Only chemotherapy, not chemoradiation, should be given for N1 disease based on currently available data. The recently published update of the Adjuvant Navelbine International Trialist Association (ANITA) randomized trial demonstrated that postoperative RT provided a survival benefit in patients with both pN1 and pN2 NSCLC disease when these patients were unable to receive adjuvant chemotherapy. REFERENCES: Lally, et al. Journal of Clinical Oncology. 2006;24(19):2998-3006. International Journal of Radiation Oncology, Biology, Physics (Int J Radiat Oncol Biol Phys). 72(3):695–701.
127.
Which of the following management steps would be most appropriate for a patient who is to undergo breast-conserving therapy with neoadjuvant chemotherapy for a 6-cm breast mass? A. Placement of a clip in the tumor before chemotherapy to mark the primary location for the surgeon in case the tumor has a complete clinical response to chemotherapy B. Biopsy of mammographic abnormalities in other quadrants of the breast after chemotherapy to rule out multicentric disease before irradiation C. No radiation therapy required if the patient has a complete pathologic response to neoadjuvant chemotherapy D. Irradiation of the supraclavicular and axillary lymph nodes even if the nodes are found to be negative after resection and administration of chemotherapy
Correct answer is A. RATIONALE: A clip needs to be placed to mark the primary tumor location for the surgeon in case of a complete clinical response to neoadjuvant chemotherapy. Multicentric disease needs to be ruled out prior to chemotherapy as well as after chemotherapy. All patients should receive postoperative irradiation, regardless of their response to chemotherapy. Regional lymph node irradiation is controversial, but was not required in the randomized NSABP B-18 and B-27 trials. REFERENCES: Buchholz, et al. Journal of Clinical Oncology. 2008;26:791-7. Rastogi, et al. Journal of Clinical Oncology. 2008;26:778-85. 128.
Which of the following best describes the shape of the radiation dose response curve for dicentric chromosomal aberrations in peripheral blood lymphocytes? A. B. C. D.
A linear-quadratic dose response following low-LET irradiation at a low dose rate A linear-quadratic dose response following low-LET irradiation at a high dose rate A quadratic dose response following low-LET irradiation at a high dose rate A linear-quadratic dose response following high-LET irradiation at a high dose rate
Correct answer is B. RATIONALE: Dicentrics require two chromosomal breaks to form. For low-LET radiation, a small fraction of these form from single particle traversals and the rest from the traversal of two separate particles, leading to a linear-quadratic dose response overall. At low dose rates, these single particle events dominate, causing the quadratic term to approach zero and the dose response to become essentially linear. On the other hand, for high-LET radiation, two breaks caused by single particle traversals dominate, likewise yielding a linear dose response. However, the linear dose response curve for dicentrics is steep for high-LET irradiation (regardless of dose rate) and shallow for low-LET irradiation at a low dose rate. REFERENCE: Mettler and Upton. Medical Effects of Ionizing Radiation. 3rd edition, Chapter 3 (Figure 3-9 in particular). 129.
In a linear regression model, what is the meaning of R2? A. B. C. D.
It is the mean square error. It is the square of the significance level. It is the percent of variance explained by the model. It is a measure of the degree to which the data are skewed.
Correct answer is C. RATIONALE: R2, the square of the correlation, can be shown to be the variance explained by the regression model divided by the total variance. That is, it is the percent of variance explained by the model.
130.
Which of the following pathologic factors is an absolute indication for concurrent adjuvant chemoradiation for high-risk patients with advanced head and neck cancer? A. B. C. D.
Multiple positive lymph nodes Extracapsular extension Lymphvascular invasion Perineural invasion
Correct answer is B. RATIONALE: This item is based on the EORTC and RTOG high-risk postoperative trials (i.e., the results of RTOG 95-01 and EORTC 22931). The initial results of RTOG 95-01 would support options A or B, but EORTC 22931 would not support option A, and the joint analysis supports only the correct answer (option B). 131.
If it takes 400 seconds to deliver 7.5 Gy to the surface of an HDR cylindrical applicator for the first treatment, how many seconds will it take to deliver the same dose 2 weeks later? (Assume the same source is used, and T1/2 of the source is 74 days.) A. B. C. D.
351 400 456 500
Correct answer is C. RATIONALE: Over the course of 2 weeks, the source will exponentially decay. To deliver the same dose, the treatment time will need to be exponentially increased as follows: T = To x exp(0.693*t/t1/2); T = 400 s x exp(0.693*14d/74d) = 456 seconds. 132.
Which of the following terms applies to the proportion of time that a diagnostic test is negative in patients who do not have the disease? A. B. C. D.
Sensitivity Specificity Standard error Subjective probability
Correct answer is B. RATIONALE: Specificity reflects the proportion of time that a diagnostic test is negative in patients who do not have the disease. 133.
Which of the following statements about halogenated pyrimidine radiosensitizers is true? A. Misonidazole produces less radiosensitization than etanidazole because it does not cross the blood-brain barrier. B. IdUrd is used preferentially to BrdUrd as a radiosensitizer because it produces less photosensitivity. C. Radiosensitization by halogenated pyrimidines is selective for slowly proliferating cells. D. Halogenated pyrimidine radiosensitizers are selectively toxic to tumor cells.
Correct answer is B. RATIONALE: The halogenated pyrimidine IdUrd is preferred to BrdUrd because it produces comparable radiosensitization, but significantly less photosensitization, a troublesome side effect in patients receiving BrdUrd. Misonidazole and etanidazole are not halogenated pyrimidines. Halogenated pyrimidines are selective radiosensitizers of rapidly proliferating cells, whether they derive from tumors or normal tissues. REFERENCE: Hall and Giaccia. Radiobiology for the Radiologist. 6th edition, Chapter 25.
134.
Which of the following statements about integrating paclitaxel into a regimen of doxorubicin/cyclophosphamide (AC) chemotherapy, surgery, and radiation therapy for treatment of breast cancer is true? A. Radiation therapy is best sequenced between AC chemotherapy and paclitaxel because of increased radiation toxicity after paclitaxel. B. In patients undergoing breast-conserving therapy, the local recurrence rate is unchanged in patients receiving AC chemotherapy compared with AC chemotherapy plus paclitaxel. C. Concurrent weekly paclitaxel during radiation therapy is associated with a higher risk of pneumonitis. D. Concurrent paclitaxel and dose-reduced radiation therapy result in improved local control rates when compared to AC chemotherapy → paclitaxel → radiation therapy outcomes.
Correct answer is C. RATIONALE: Radiation is usually sequenced after AC chemotherapy and paclitaxel. In a randomized study (CALGB 9344), AC chemotherapy and paclitaxel in patients treated with breast-conserving surgery and radiation therapy was associated with a lower local recurrence rate at 5 years compared to AC chemotherapy alone. There was no detriment in radiation therapy delivery or radiation therapy tolerance after paclitaxel. Twenty-five percent of patients had dose-limiting toxicity, including pneumonitis, with concurrent radiation therapy and paclitaxel in a study. REFERENCES: Journal of Clinical Oncology. 2005;23:30-40. Burstein, et al. International Journal of Radiation Oncology, Biology, Physics (Int J Radiat Oncol Biol Phys). 2006;64:496-504. 135.
According to the INT-0116 (Macdonald) study, which of the following was associated with postoperative chemoradiation and chemotherapy (3 cycles) versus surgery alone for resected gastric cancer? A. Control of metastatic disease was improved with adjuvant therapy, leading to improved overall survival. B. Locoregional control was improved with adjuvant therapy, leading to improved overall survival. C. An increase in deaths was associated with adjuvant therapy, eliminating any survival benefit. D. The study used cisplatin/5-fluorouracil (5-FU) chemotherapy.
Correct answer is B. RATIONALE: The INT-0116 study showed a survival benefit directly related to locoregional control. No difference in metastatic rate was seen. The study was positive by intent-to-treat. The backbone of chemotherapy was 5-fluorouracil/leucovorin (5-FU/LV). REFERENCE: New England Journal of Medicine (NEJM). 2001.
136.
According to NRC regulations, acceptance tests of a new HDR treatment planning system do NOT require verification of the: A. effectiveness of the optimization algorithm to achieve the best treatment plan. B. accuracy of dose, dwell time, and treatment time calculations at representative points. C. accuracy of the software used to determine sealed source positions from radiographic images. D. accuracy of isodose plots and graphic displays.
Correct answer is A. RATIONALE: According to 10 CFR Part 35.657, the effectiveness of the optimization algorithm to achieve the best treatment plan is not a minimum requirement of the acceptance test procedure to verify in the therapy-related treatment planning system. 137.
Which of the following AJCC staging criteria for NSCLC is correct? A. B. C. D.
Tumor invasion of the carina is T3. Tumor invasion of the phrenic nerve is T4. Involvement of the ipsilateral supraclavicular lymph node is N3. Involvement of the contralateral mediastinal lymph node is N2.
Correct answer is C. REFERENCE: AJCC lung cancer staging. AJCC Cancer Staging Manual, 6th edition. 138.
What is the probability of occult metastasis to the inguinofemoral lymph nodes of a 2.5-cm squamous cell carcinoma of the vulva classified as clinical stage T2N0M0? A. B. C. D.
10% 20% 30% 40%
Correct answer is C. RATIONALE: Clinical tumor size correlates with occult metastases in patients with clinically negative lymph node involvement as follows: 0 to 1 cm = 7.7%; 1.1 to 2 cm = 23.9%; 2.1 to 3 cm = 31%; 3.1 to 5 cm = 36.4%. REFERENCE: Adapted from Gonzalez, et al. International Journal of Radiation Oncology, Biology, Physics (IJROBP). 2003;57:419-424. 139.
Spheroids are used as a model system for: A. B. C. D.
small preangiogenic tumors. large angiogenic tumors. tumors suppressed by the immune system. apoptosis.
Correct answer is A. RATIONALE: Multicellular spheroids are a model system for studying radiation effects that combine the convenience and control of a cellular assay with the three dimensional structure, cell-cell contact, and nutrient and oxygen gradients more reminiscent of tumors in vivo. As large spheroids can reach sizes of 1-2 mm in diameter, they can be considered good models for small, pre-angiogenic tumors.
140.
A Kaplan-Meier survival curve yields a 1-year survival probability of 0.45 and an associated standard error of 0.07. The 95% confidence interval for the 1-year survival probability is approximately: A. B. C. D.
0.40 to 0.50. 0.38 to 0.52. 0.31 to 0.59. 0.29 to 0.61.
Correct answer is C. RATIONALE: The 95% confidence bounds are computed as the value of interest (approximately +2X the standard error). In this case, the 95% confidence interval is computed as follows: 0.45 +2(0.07), which equals approximately 0.31 to 0.59. 141.
Which of the following statements about heterotrophic ossification is true? A. Its incidence is 10% in patients with moderate or severe osteophytes at the femoral head and socket before hip replacement. B. Radiographically detected calcifications are not seen before 3 months postoperatively. C. The radiation field is 8 x 8 cm, is approximately 3 cm above the acetabulum, and excludes two thirds of the implant shaft. D. Preoperative radiation treatment with 7 to 8 Gy in 1 fraction is equally effective as the same treatment given postoperatively.
Correct answer is D. RATIONALE: Option A: The incidence of heterotrophic ossification is more than 50% in these patients. Option B: Calcified structures are seen as early as 3 to 6 weeks postoperatively, and patients may report increased pain from heterotrophic bone formation within several days after their surgery. Option C: The irradiation field that covers the entire periarticular risk region will be approximately 14 x 14 cm. The cranial border is 3 cm above the acetabulum, and the field includes two thirds of the implant shaft. Option D: In three randomized trials, there was no significant difference in effectiveness of high and low doses or difference between fractionated and single-dose therapy. REFERENCE: Gunderson & Tepper, eds. Clinical Radiation Oncology. 2nd edition. 2007;1561-1562. 142.
The beam stop on a linear accelerator should transmit only 0.1% of the incident radiation beam. What additional shielding expressed in half value layers (HVL) is required to reduce the transmission from 1.6% to 0.1%? A. B. C. D.
2 HVL 3 HVL 4 HVL 5 HVL
Correct answer is C. RATIONALE: This item tests knowledge of the concept of HVL; 1.6% x 0.5 x 0.5 x 0.5 x 0.5 = 0.1%. Hence, 4 HVL are needed.
143.
Which of the following statements about the use of chemotherapy in addition to radiation therapy for squamous cell carcinoma of the head and neck is true? A. Neoadjuvant chemotherapy is superior to concomitant chemotherapy. B. Polychemotherapy is more effective than monochemotherapy. C. The effect of chemotherapy on patient survival significantly decreases with increasing age. D. The absolute benefit of concurrent chemotherapy is less than 5%.
Correct answer is C. RATIONALE: Based on the recently updated meta-analysis of chemotherapy in head and neck cancer (MACH0NC), concomitant chemotherapy was most effective when compared to neoadjuvant and adjuvant chemotherapy with an absolute survival benefit of 8% at 5 years. No significant difference was seen between monochemotherapy and polychemotherapy. For the effect of chemotherapy on survival by covariate values (sex, age, performance status, tumor stage, nodal stage, overall stage, and tumor site), the only significant interaction was a decreasing effect of chemotherapy with increasing age (test for trend, p=0.003). REFERENCE: International Journal of Radiation Oncology, Biology, Physics (Int J Radiat Oncol Biol Phys). 2007;69:112-114. 144.
Which of the following sites of pathologic bone fracture occurs most commonly secondary to metastatic cancer, regardless of the primary tumor site? A. B. C. D.
Humerus Acetabulum Femoral shaft Subtrochanteric femur
Correct answer is D. RATIONALE: Option A: 17%; option B: 8.5%; option C: 10%; option D: 21%. REFERENCES: Mirels H. Metastatic disease in long bones: a proposed scoring system. Clinical Orthopedics. 1989;249-256. Gunderson & Tepper, eds. Clinical Radiation Oncology. 2nd edition. 2007;437- 449. 145.
Which of the following statements about bone metastases secondary to breast cancer is true? A. Approximately 15% of patients have osteoblastic lesions. B. Samarium is equally effective for osteolytic and osteoblastic lesions. C. The 5-year survival rate in patients with isolated bone metastases is approximately 65%. D. Pamidronate (Aredia) administered for lytic bone metastases does not affect the subsequent risk of pathologic fractures.
Correct answer is A. RATIONALE: Options A, B, and C: Five-year survival with metastatic disease to the bone only is 40%. Samarium is effective only with blastic lesions. Approximately 15% of patients with breast cancer have osteoblastic metastatic disease. Patients with lytic bone metastases were given pamidronate IV q. 4 weeks x 24 cycles had a skeletal complication rate of 56% compared with 67% in the control group. The most common skeletal complication was pathologic fracture, and this occurred in 45% of patients receiving pamidronate and in 55% of the placebo patients (p.054). REFERENCES: Harris, Lippman, Morrow, and Osborne. Diseases of the Breast. 3rdedition. 2004;1001-1159. Theriault, et al. Pamidronate reduces skeletal morbidity on women with advanced breast cancer and lytic bone lesions: a randomized placebo-controlled trial. Journal of Clinical Oncology (JCO). 1999;17(3):846-854.
146.
Which of the following treatment modalities should be recommended for a patient with a stage II, centrally located NSCLC that is medically inoperable? A. B. C. D.
Conventional fractionated radiation therapy (66 Gy in 33 fractions) Stereotactic body radiation therapy (60 Gy in 3 fractions) Radiofrequency ablation Cryotherapy
Correct answer is A. RATIONALE: The central location of the cancer makes this patient a poor candidate for stereotactic body radiation therapy (SBRT), which would cause a higher rate of airway stenosis. Radiofrequency ablation has not been established as definitive therapy. Cryotherapy can be useful for palliation of endobronchial disease. 147.
Which of the following statements about the behavior of tumor cells after exposure to ionizing radiation is true? A. The presence of chromosomal aberrations within 24 hours of irradiation is a predictor of apoptotic cell death. B. Apoptosis within 3 days after irradiation is a reliable surrogate marker for clonogenic survival. C. Clonogenic cell survival is defined as the ability of cells to form colonies of at least 50 cells. D. The "gold standard" for measuring cellular radiation sensitivity is the ability of cells to proliferate for 5 days following irradiation.
Correct answer is C. RATIONALE: Clonogenic survival assays are considered the "gold standard" for measuring cellular radiation sensitivity, but they take at least a week to complete, and often, twice that or more. Shorter-term survival assays, however, although informative in and of themselves and more convenient in some situations, typically do not correlate well with clonogenic survival. 148.
What percent of pituitary adenomas are secretory tumors? A. B. C. D.
10% 30% 50% 70%
Correct answer is D. RATIONALE: The majority of pituitary adenomas (70%) are secretory. 149.
A poor overall prognosis is associated with women who have urethral carcinoma involving the: A. B. C. D.
meatus. distal urethra. proximal urethra. periurethral glands of Skene.
Correct answer is C. RATIONALE: Tumors of the distal urethra and meatus are typically early stage and superficially invasive in women with urethral carcinoma. In contrast, tumors arising in the proximal urethral typically are more deeply invasive and associated with a poorer outcome.
150.
Before thermoluminescent materials can be read, they must be: A. B. C. D.
cooled. heated. charged. discharged.
Correct answer is B. RATIONALE: Thermoluminescent materials use heat to stimulate the emission of light from a molecular or crystal matrix following its exposure to ionizing radiation as a means of quantifying dose. Therefore, in order to read a TLD, the material must be heated. 151.
Hypoxic cells in tumors are: A. B. C. D.
resistant to neutron irradiation. resistant to photon irradiation. sensitive to proton irradiation. sensitive to photon irradiation.
Correct answer is B. RATIONALE: Relative to aerobic cells, hypoxic cells are more resistant to low-LET types of ionizing radiation (X-rays and protons), but equally sensitive to high-LET types of ionizing radiation (neutrons). REFERENCE: Hall and Giaccia. Radiobiology for the Radiologist. 6th edition, Chapter 7. 152.
Loss of heterozygosity of chromosomes 1p/19q in patients with oligodendroglioma does NOT predict which of the following outcomes? A. B. C. D.
Radiographic response to chemotherapy Overall survival after radiation therapy alone Overall survival after chemotherapy alone Tumor resectability
Correct answer is D. RATIONALE: 1p/19q LOH predicts better response and survival after both chemotherapy and radiation therapy. The ability to completely resect a tumor is not predicted by 1p/19q status. 153.
Which of the following statements about the use of cetuximab for squamous cell carcinoma of the head and neck is true? A. B. C. D.
It should be given after completion of radiation therapy. It should be initiated simultaneously with radiation therapy. A loading dose is required 1 week before beginning radiation therapy. It is more effective when given every 3 weeks rather than weekly.
Correct answer is C. RATIONALE: A loading dose of 400 mg/M2 should be given 1 week before beginning radiation therapy to saturate the EGFR, and then given weekly during the course of radiation therapy. REFERENCE: Bonner, et al. New England Journal of Medicine (NEJM). 354(6):567-8.
154.
Which of the following advantages is associated with proton therapy versus photon therapy? A. B. C. D.
Proton beams have a sharper penumbra. Proton beams have a higher LET. Proton therapy has a lower integral dose. Proton therapy uses higher energy beams.
Correct answer is C. RATIONALE: Proton beams typically deliver approximately less than half of the integral dose compared to photon beams for the same target dose. 155.
Which of the following outcomes was demonstrated by the GETUC-01 phase III trial, which compared radiation therapy to the prostate alone versus whole-pelvis radiation therapy for patients with prostate cancer? A. Whole-pelvic radiation therapy improved progression-free survival for high-risk patients. B. Whole-pelvis irradiation decreased lymph node failure. C. Whole-pelvis radiation therapy resulted in greater chronic GU and GI toxicity. D. No improvement in progression-free survival was observed.
Correct answer is D. RATIONALE: The result of this phase III trial published in the Journal of Clinical Oncology helps to define the role of pelvic irradiation for patients who have clinically localized prostate cancer with clinically negative lymph nodes. This trial showed no survival benefit with whole-pelvic irradiation when compared to prostate irradiation alone. 156.
According to the Lung Intergroup 0139 trial, which of the following outcomes was demonstrated in the trimodality arm for patients with stage IIIA NSCLC? A. B. C. D.
There was a statistically significant improvement in disease-free and overall survival. There was a statistically significant improvement in local control. A complete resection was achieved in only 50% of patients. The trimodality treatment approach offered the best survival rate when a pneumonectomy was incorporated.
Correct answer is B. RATIONALE: Seventy-one percent of patients had a complete resection. The local relapse rate after trimodality treatment was significantly improved (10% vs. 22%), and the disease-free survival rate also was significantly improved. There was a trend for increased 5-year overall survival associated with the trimodality approach; however, that is not optimal when a pneumonectomy is required due to the increase in mortality rates. 157.
According to the GOG (Creasman) trial, what is the risk for pelvic lymph node metastasis in patients with stage I, grade 2 endometrial adenocarcinoma invading the middle one third of the myometrium? A. B. C. D.
<5% 08% to 15% 18% to 25% 28% to 35%
Correct answer is B. REFERENCE: Creasman. GOG trial. Cancer. 1987;60:2035-2041. These tables provide a rationale for which patients need pelvic radiation for coverage of pelvic lymph nodes if not dissected.
158.
The highest risk of mental retardation occurs when an embryo or fetus is irradiated during which stage of gestation? A. B. C. D.
00 to 3 weeks 04 to 7 weeks 08 to 15 weeks 16 to 25 weeks
Correct answer is C. RATIONALE: There is a high risk of mental retardation, approaching 40% risk per Sievert, if the fetus is irradiated between 8 and 15 weeks of gestation. The risk is 4 times lower – although still elevated – if irradiation occurs between 15 and 25 weeks. REFERENCE: Hall and Giaccia. Radiobiology for the Radiologist. 6th edition, Chapter 12. 159.
Based on the results of the United Kingdom START A and START B trials, which of the following whole-breast radiation fractionation schedules was used? A. B. C. D.
41.6 Gy delivered in 13 fractions, 3.2 Gy per fraction 4 days each week for 3 weeks 40 Gy delivered in 15 fractions, 2.67 Gy per fraction 5 days each week for 3 weeks 40 Gy delivered in 10 fractions, 4 Gy per fraction 5 days every 2 weeks for 4 weeks 39 Gy delivered in 13 fractions, 3 Gy per fraction 5 days each week for 2½ weeks
Correct answer is B. RATIONALE: The START A and B trials compared different whole-breast hypofractionation schedules to 50 Gy in 2 Gy fractions over 5 weeks. The START A trial used 41.6 Gy or 39 Gy in 13 fractions but used 5 fractions every 2 weeks to maintain an elapsed time of 5 weeks. The START B trial used 40 Gy in 15 fractions 5 days a week over an elapsed time of 3 weeks. REFERENCES: Lancet Oncology. 2008;9:331-41. Lancet. 2008;371:1098-107. 160.
Which of the following isotopes is currently used for permanent seed prostate implants? A. B. C. D.
103
Pd Ir 60 Co 131 I 192
Correct answer is A. RATIONALE: 103Pd is a commonly used radioactive source for permanent prostate seed implant. Its relatively short half-life (17 days) and low average energy (21 keV) make it a good candidate for permanent seed implants. The energies of the emitted photons for 192 Ir and 60Co are much higher, and as a result, are more penetrating, making them impractical for permanent implants. P-32 is a pure beta emitter and has a short range of penetration.
161.
Which of the following statements about chondrosarcoma is true? A. Thirty percent of chondrosarcomas are high-grade lesions. B. Primary lesions can develop from a preexisting chondroid lesion. C. Primary chondrosarcomas are typically peripheral, arising from the surface of the bone. D. A favorable prognosis is strongly correlated with histological grade and adequate surgical excision.
Correct answer is D. RATIONALE: Option A: 5% to 10% of chondrosarcomas are high-grade lesions. These lesions have a high potential to metastasize. Option B: Primary lesions are not associated with preexisting lesions. Secondary lesions develop from preexisting chondroid lesions, such as enchondroma or osteochondroma. Option C: Chondrosarcomas are classified as central when they arise from the medullary cavity and peripheral when they arise from the surface of bone. Primary chondrosarcomas are nearly always central; secondary chondrosarcomas can be central or peripheral. Option D: Prognosis is generally favorable and is strongly correlated histologic grade and adequacy of surgery. REFERENCE: Chow W.A. Update on chondrosarcomas. Current Opinion in Oncology. 2007;19:371-376. 162.
According to the phase III GOG 92 (Sedlis) randomized trial, adjuvant radiation therapy for patients with high-risk, node-negative cervical cancer consisted of: A. B. C. D.
pelvic irradiation alone. vaginal brachytherapy alone. pelvic irradiation plus vaginal brachytherapy. pelvic plus paraaortic lymph node irradiation.
Correct answer is A. RATIONALE: GOG Trial 92 randomized patients with high-risk nodenegative cervical cancer following radical surgery to either pelvic irradiation alone or no further therapy. All patients had at least two of the following risk factors: >1/3 stromal invasion, capillary space involvement, and large clinical tumor diameter. REFERENCE: Sedlis, et al. Gynecological Oncology. 1999;73:177. 163.
Which of the following radiation fractionation schedules used to treat bone metastases provides the highest biological effective dose (BED) for symptomatic relief? A. B. C. D.
08 Gy in 1 fraction 20 Gy in 5 fractions 30 Gy in 10 fractions 40.5 Gy in 15 fractions
Correct answer is D. RATIONALE: Summary of prospective trials for radiation therapy used for treatment of painful osseous metastases suggests schedules with higher biological effective doses (BED) resulted in better pain relief and reduced the need for retreatment. REFERENCE: Gunderson & Tepper, eds. Clinical Radiation Oncology. 2nd edition, 2007;443-445.
164.
Classic Kaposi sarcoma (occurring in an elderly male of Mediterranean ancestry) most commonly is observed first on the skin of the: A. B. C. D.
lower legs. palms. trunk. face.
Correct answer is A. RATIONALE: The initial distribution of classic Kaposi sarcoma (KS) virtually always is on the lower legs (followed occasionally by the palms and rarely the mucosa of the oral cavity); whereas there is far less predictability for other types of KS. 165.
The extrinsic death receptor and intrinsic mitochondrial apoptotic pathways converge on: A. B. C. D.
caspase-2. caspase-3. caspase-8. caspase-9.
Correct answer is B. RATIONALE: Caspase-3 is an effector caspase whose activation by either the extrinsic or intrinsic apoptotic signaling pathways commits the cell to programmed suicide. 166.
Which of the following genetic alterations is present in the majority of patients with pancreatic ductal adenocarcinomas? A. B. C. D.
MDM2 amplification K-ras gene mutation Platelet-derived growth factor receptor mutation Deletion of the PTEN tumor suppressor gene
Correct answer is B. RATIONALE: Targeted-based therapies are becoming a critical component of oncology therapy, and in some sites, such as the colon, the mutation status of Kras is predictive of a therapeutic response. 167.
The anisotropy function in the brachytherapy dose calculation for a line source accounts for the: A. B. C. D.
difference in the dose around the source due to self-absorption. decay of the source activity between the date of calibration and the date of implant. falloff of dose as the inverse of the distance squared. radial dependence of photon scattering and attenuation in a medium.
Correct answer is A. RATIONALE: According to AAPM TG report 43, the anisotropy function, F(r, θ), accounts for the variation in dose as a function of polar angle relative to the transverse plane of the source.
168.
What is the AJCC stage for a patient who has prostate cancer with invasion of the ipsilateral seminal vesicles? A. B. C. D.
T2b T3a T3b T4
Correct answer is C. RATIONALE: Straight-forward question on AJCC staging of prostate cancer. REFERENCE: AJCC Cancer Staging Manual, 6th edition. 169.
Which of the following radiation sensitizers combined with postoperative radiation therapy has been shown to improve the outcome of high-risk patients with advanced head and neck cancer? A. B. C. D.
Cisplatin every 3 weeks Mitomycin and cisplatin every 3 weeks Cetuximab weekly Cisplatin weekly
Correct answer is A. RATIONALE: This item is based on the EORTC and RTOG high-risk postoperative trials (ie, RTOG 95-01 and EORTC 22931). 170.
Which of the following proteins is a stimulator of angiogenesis? A. B. C. D.
Thrombospondin-1 (TSP-1) Tissue inhibitor of matrix metalloproteinases-3 (TIMP-3) Basic fibroblast growth factor (bFGF) Angiopoeitin-1 (Ang-1)
Correct answer is C. RATIONALE: Basic fibroblast growth factor (bFGF) is one of several known promoters of angiogenesis (the best known is VEGF, vascular endothelial growth factor), whereas the other proteins listed are inhibitors of angiogenesis. 171.
What is the expected incidence of inguinal lymph node metastasis in a patient with a 2-cm squamous cell carcinoma of the vulva with a depth of invasion of 5.5 mm? A. B. C. D.
06% 08% 22% 37%
Correct answer is D. RATIONALE: Pooled data from vulvar series notes the following correlation of incidence of groin lymph node metastases in patients with primary tumors of 2 cm or less and the following depths of invasion: 1 mm or less = 0%; 1.1 to 2 mm = 6.6%; 2.1 to 3 mm = 8.2%; 3.1 to 4 mm = 22.0%; 4.1 to 5 mm = 25.0; and >5 mm = 37.5%.
172.
After electrons exit a linear accelerator, which of the following is the dominant process by which a clinical photon beam is produced? A. B. C. D.
Photoelectric effect Compton scattering Electron scattering Bremsstrahlung
Correct answer is D. RATIONALE: Bremsstrahlung ("braking radiation") in the linearaccelerating (linac) target is the dominant effect producing photons from electrons. 173.
Which of the following agents is most effective when combined with cisplatin for treatment of mesothelioma? A. B. C. D.
Pemetrexed Gemcitabine Navelbine Docetaxel
Correct answer is A. RATIONALE: In a randomized phase III trial, pemetrexed plus cisplatin was associated with improved survival compared with cisplatin alone for patients with malignant pleural mesothelioma (MPM). Median time to progression was significantly longer in the pemetrexed/cisplatin arm: 5.7 months versus 3.9 months (P =.001). Response rates were 41.3% in the pemetrexed/cisplatin arm versus 16.7% in the control arm (P <.0001). REFERENCE: Journal of Clinical Oncology. July 15, 2003;21(14):2636-44. 174.
According to the German Rectal Cancer Study Group (Sauer) trial, what was the pathologic complete response rate to preoperative chemoradiation for patients who have rectal cancer? A. B. C. D.
08% 18% 28% 38%
Correct answer is A. RATIONALE: The German trial is one of the most important recent studies on rectal cancer. The pathologic complete response (CR) rate was reported. REFERENCE: Sauer, et al. New England Journal of Medicine (NEJM). 2004;351:1731-40. 175.
Temsirolimus (Torisel) is a recently approved targeted therapy for metastatic renal cell carcinoma that inhibits which of the following types of protein? A. B. C. D.
Vascular endothelial growth factor (VEGF) Epidermal growth factor receptor (EGFR) Mammalian target of rapamycin (mTOR) Platelet-derived growth factor (PDGF)
Correct answer is C. RATIONALE: Temsirolimus is a mammalian target of rapamycin (mTOR) inhibitor, which has been shown to be efficacious for metastatic renal cell carcinoma.
176.
Which of the following signaling pathways is thought to be responsible for EGFR overexpression in human cancer cells? A. B. C. D.
IKκB → NFκB Ras → JNK Ras → Raf → MAPK PI3K → AKT → mTOR
Correct answer is C. RATIONALE: The epidermal growth factor receptor (EGFR) is one of a family of four closely related transmembrane receptors that use tyrosine kinase activity as the signal transduction trigger. EGFR is frequently overexpressed in human epithelial cancers, and as such, constitutes an attractive target for cancer prevention and treatment. Once the tyrosine kinase is triggered, the signal is transduced through the Ras → Raf → MAPK pathway, which regulates several processes involved in tumor cell survival and proliferation, including the inhibition of apoptosis, increased radiation and chemotherapy resistance, stimulation of angiogenesis, promotion of metastasis and, ironically, further overexpression and activation of EGFR. 177.
FIGO stage IIIA is associated with cervical cancer that extends to which of the following anatomic sites? A. B. C. D.
Pelvic sidewall Lower uterine segment Upper one third of the vagina Lower one third of the vagina
Correct answer is D. RATIONALE: The FIGO staging system in cervical cancer divides stage III into IIIA lesions (i.e., tumor involves the lower one third of the vagina with no extension to the pelvic sidewall) and IIIB (i.e., tumor extends to the pelvic wall and/or causes hydronephrosis or nonfunctioning kidney. Tumors extending into the upper two thirds of the vagina are stage IIA. Extension into the lower uterine segment is not included in the FIGO staging of cervical cancer. 178.
Based on a pooled analysis, which of the following statements about the addition of high-dose cisplatin with radiation therapy in postoperative patients with high-risk head and neck cancer is FALSE? A. B. C. D.
It improves overall survival. It improves locoregional control. It increases disease-free survival. It decreases distant metastasis.
Correct answer is D. RATIONALE: Based on high-risk EORTC and RTOG postoperative trials, there is no difference in distant metastasis between the two arms.
179.
For quality assurance of a linear accelerator, which of the following variations in x-ray/electron beam output constancy would require action to be taken? A. B. C. D.
5% daily variation 3% daily variation 1% daily variation 1% monthly variation
Correct answer: ABCD. RATIONALE: According to AAPM TG40, the suggested action level for x-ray/electron beam output constancy is 3% for a daily check and 2% for a monthly variation of 2% for a monthly output check. 180.
Based on the Masaoka staging system for thymoma, which of the following stages is associated with macroscopic invasion into adjacent organs? A. B. C. D.
IIA IIB III IV
Correct answer is C. RATIONALE: This item refers to the Masaoka staging system. Macroscopic invasion into adjacent organs is classified as stage III disease. 181.
What would be the most appropriate adjuvant therapy after nephroureterectomy for a patient with multifocal, high-grade ureteral carcinoma with one positive lymph node and negative margins? A. B. C. D.
Chemoradiation External-beam radiation therapy Intraoperative radiation therapy Observation
Correct answer is D. RATIONALE: There are no prospective randomized trials that support adjuvant radiation therapy in this setting, especially in the setting of a negative surgical margin. 182.
Which of the following syndromes is associated with a high risk for the development of cancer and is caused by biallelic mutations in the BRCA2 gene? A. B. C. D.
Fanconi anemia Bloom's syndrome Nijmegen breakage syndrome Ataxia telangiectasia
Correct answer is A. RATIONALE: Complementation analysis of cell lines from different patients with Fanconi anemia has led to the description of at least 12 groups, named FA-A, B, C, D1, D2, E, F, G, I, J, L, and M, with the corresponding genes named as FANCA-FANCM. FANCD1 is BRCA2, and monoallelic mutations in BRCA2 cause susceptibility to breast and other cancers. Ataxia telangiectasia, Bloom's syndrome, and Nijmegen breakage syndrome are caused by mutations of ATM, BLM, and NBS1, respectively. REFERENCE: Green AM and Kupfer GM. Fanconi anemia. Hematology/Oncology Clinics of North America. 2009;23:193-214.
183.
Which of the following terms applies to a clinical trial in which each group of subjects receives two or more treatments but in different sequences? A. B. C. D.
Cross-over study Cross-sectional study Cross-validation procedure Cross-product ratio
Correct answer is A. RATIONALE: A cross-over study is applied to a clinical trial in which each group of subjects receives two or more treatments, but in different sequences. A cross-sectional study is an observational study that examines a characteristic in a set of subjects at one point in time. A cross-validation is a procedure applying the results of an analysis from one sample of subjects to a new sample of subjects to evaluate how well they generalize. A cross-product ratio is similar to relative risk. 184.
Which of the following radioisotopes is most commonly used in HDR brachytherapy for patients who have cervical cancer? A. B. C. D.
125
I Cs 192 Ir 198 Au 137
Correct answer is C. RATIONALE: Several isotopes are currently available for brachytherapy in patients with cervical cancer. Iridium-192 is the most popular HDR source; cesium-137 is the most popular source used in LDR brachytherapy. 185.
Which of the following factors would increase the percent depth dose the most due to an increase in the SSD? A. B. C. D.
Change in lateral scatter Change in field size Inverse square law Beam hardening
Correct answer is C. RATIONALE: Although the PDD will be affected due to an increase in SSD by a change in scatter, field size, and inverse square law, the largest influence will be the due to the increased distance from the source (option C). In this scenario, the PDD will increase by the inverse of the distance squared. Beam hardening will not be influenced if the depth in tissue remains constant and we consider the attenuation in air to be negligible. 186.
Which of the following forms of leukemia is most appropriately treated with imatinib (STI571)? A. B. C. D.
Acute lymphocytic Acute myelogenous Chronic lymphocytic Chronic myelogenous
Correct answer is D. RATIONALE: Imatinib is a tyrosine kinase inhibitor that is indicated for GI stromal tumors (GIST) and chronic myelogenous leukemia (CML). REFERENCE: FDA package insert.
187.
A clinical trial must have which of the following characteristics? A. B. C. D.
A control group A prospective plan that involves human subjects A predetermined, fixed sample size Treating physicians or patients blinded to treatment received
Correct answer is B. RATIONALE: Some clinical trials have only a single arm, with data from an already completed study as the (historical) control. The control arm, if there is one, may receive no treatment, a sham treatment, or an alternative, active treatment. Sample size may be altered during the course of a trial of any phase based on outcomes observed during the trial. Blinding can help to reduce treatment-related bias, but it is not essential. 188.
According to Michalowski's tissue classification system, bone marrow would be classified as which of the following types of tissue? A. B. C. D.
Consolidated Flexible Hierarchical Mature
Correct answer is C. RATIONALE: Michalowski's system classifies normal tissues according to whether they contain stem cells, transit-amplifying cells and differentiated, functioning cells, or whether they appear to only (or mostly) contain mature, functioning cells. Type H or "hierarchical" tissues contain both stem, transit, and mature cells, with each type discretely located in its own anatomically or histologically distinct "compartment" within the tissue. Examples include the bone marrow, the intestinal epithelium, and the epidermis of the skin. Type F or "flexible" tissues show no strict hierarchy or histologically identifiable compartments, but only appear to be composed of differentiated, functioning cells (or in a few cases, of mature cells that can revert to stem cells and back in response to an injury). Examples include the central nervous system, muscle, heart, and liver. REFERENCE: Hall and Giaccia. Radiobiology for the Radiologist. 6th edition, Chapter 19. 189.
Which of the following gene mutations has been shown to predict a patient's response to cetuximab therapy when used as second-line treatment of metastatic colorectal cancer? A. B. C. D.
Akt K-ras EGFR VEGF
Correct answer is B. REFERENCE: Lièvre A, Bachet JB, Le Corre D, Boige V, Landi B, Emile JF, Côté JF, Tomasic G, Penna C, Ducreux M, Rougier P, Penault-Llorca F, Laurent-Puig P. Kras mutation status is predictive of response to cetuximab therapy in colorectal cancer. Cancer Research. Apr 15, 2006;66(8):3992-5.
190.
According to the NRC, a female radiation worker is considered pregnant: A. B. C. D.
from the date of conception. when she begins to display visible signs of pregnancy. when she verbally declares her pregnancy to her employer. when she declares her pregnancy in writing to her employer.
Correct answer is D. RATIONALE: According to 10 CFR 20.1003, a woman must declare her pregnancy to her employer/licensee, in writing, along with the estimated date of conception. 191.
Which of the following types of leukemia has the highest incidence? A. B. C. D.
Acute myelogenous Acute lymphocytic Chronic myelogenous Chronic lymphocytic
Correct answer is D. RATIONALE: It's important to know which type of leukemia presents most frequently. Chronic lymphocytic leukemia (CLL) is most common. 192.
Bladder conservation therapy involving TURBT and chemoradiation would be most appropriate to recommend for patients with: A. B. C. D.
T1 multifocal TCC. T2a TCC of the lateral wall of the bladder. T2b TCC with concurrent carcinoma in-situ. T3b TCC and hydronephrosis.
Correct answer is B. RATIONALE: Option B depicts the most appropriate patient to consider for TURBT and chemoradiation. The other patients have relative contraindications or factors that have been shown to have a negative impact on outcome in prospective trials. 193.
Which of the following characteristics is associated with a diagnosis of retinoblastoma? A. Eighty percent of children are diagnosed in the first year of life. B. Approximately 80% of children with bilateral disease have a family history of the disease. C. Children who present with bilateral disease are usually 2 years older than those who present with unilateral involvement. D. It is rare in children older than 6 years of age.
Correct answer is D. RATIONALE: Eighty percent of children with retinoblastoma are diagnosed before 3 years of age. There is a family history of the disease in approximately 20% of children diagnosed with bilateral retinoblastoma. Patients with bilateral disease usually present at a younger age (14–16 months) than patients with unilateral disease (29–30 months). The diagnosis of retinoblastoma in children 6 years or older is extremely rare. REFERENCE: Chintagumpala, et al. The Oncologist. October 2007;12(10):1237-1246.
194.
Which of the following statements about pleural mesothelioma is true? A. B. C. D.
The epithelial subtype has the worst prognosis. It does not spread to the mediastinal lymph nodes. Thirty percent of cases are associated with a history of asbestos exposure. Combined modality therapy results in an overall median survival of 14 to 16 months.
Correct answer is D. RATIONALE: Patients with mixed or sarcomatous cell disease or mediastinal lymph node involvement have a worse overall survival. Seventy percent to eighty percent of mesothelioma cases were associated with a history of asbestos exposure. Patients who receive combined modality treatment for mesothelioma have an overall median survival of about 14 to 16 months. 195.
In eukaryotic cells, chromosomes are duplicated during which stage of the cell cycle? A. B. C. D.
Anaphase Interphase Metaphase Prophase
Correct answer is B. RATIONALE: Chromosomal material is replicated during the S phase of the cell cycle, a part of interphase that includes the G1, S, and G2 phases. The other options are sub-phases of mitosis (M phase), that portion of the cell cycle when the already-duplicated chromosomes are evenly segregated into daughter cells. 196.
Which of the following statements about patients who have locoregional recurrence of breast cancer after modified radical mastectomy with or without systemic and/or endocrine therapy and no radiation therapy is true? A. Median time to local recurrence is 3 years. B. The majority of recurrences present as a skin rash over the chest wall. C. Regional recurrence in the axillary, supraclavicular, and/or internal mammary lymph nodes occurs in about 10% of cases. D. The axillary lymph nodes are the most common site of regional lymph node recurrence.
Correct answer is A. RATIONALE: Median time to postmastectomy recurrence is 3 years. The majority of recurrences present as skin or subcutaneous nodules in the flaps around the mastectomy scar. Regional recurrence in the axillary, supraclavicular, or internal mammary lymph nodes occurs in 30% to 40% of cases with a local recurrence. The supraclavicular lymph nodes are the most common site of regional recurrence and occur in 11% to 35% of patients. REFERENCE: Harris, Lippman, Morrow, and Osborne. Diseases of the Breast. 3rd edition. 2004;1067.
197.
The dose chamber is located between which of the following two objects in a megavoltage linear accelerator? A. B. C. D.
Wedge tray and the block tray X-ray production target and the patient Electron gun and the accelerating waveguide Klystron and the accelerating waveguide
Correct answer is B. RATIONALE: The dose chamber is located between the x-ray production target and the patient in a megavoltage linear accelerator. It is used to monitor x-rays, and therefore, the dose delivered to the patient. 198.
Approximately what percent of patients with NSCLC present with stage III disease? A. B. C. D.
10% 20% 30% 50%
Correct answer is C. RATIONALE: According to AJCC 2002, stage I = 25%, stage II = 7%, stage III = 32%, and stage IV = 36%. Therefore, the majority of patients will have advancedstage lung cancer at diagnosis. REFERENCE: AJCC Cancer Staging Manual, 6th edition. 199.
The concurrent addition of cetuximab to radiation therapy for squamous cell carcinoma of the head and neck significantly increases: A. B. C. D.
oral mucositis. overall survival. disruption of radiation therapy. treatment-related diarrhea.
Correct answer is B. RATIONALE: The concurrent use of cetuximab with radiation therapy demonstrated significantly improved median survival, overall survival, and locoregional control. It also resulted in acneiform rash, but not oral mucositis. REFERENCE: Bonner, et al. New England Journal of Medicine (NEJM). 354:6.567-8. 200.
Which of the following types of tumor is most often associated with EGFR amplification? A. B. C. D.
Anaplastic oligodendroglioma Low-grade glioma De novo glioblastoma Ependymoma
Correct answer is C. RATIONALE: EGFR-based strategies are currently being employed in clinical trials for glioblastoma. EGFR amplification is noted in de novo glioblastoma, but not in those glioblastomas that arise from lower-grade neoplasms. These tumors appear to be molecularly distinct and may respond to different treatment strategies.
201.
Which of the following statements about the incidence of esophageal cancer in the United States is true? A. Squamous cell carcinomas are becoming more common. B. There has been a six-fold increase in esophageal adenocarcinoma over the last 25 years. C. The incidence of esophageal cancer is decreasing due to screening programs for Barrett's disease. D. The proximal esophagus is the most common location of esophageal cancer.
Correct answer is B. REFERENCE: Pohl H and Welch HG. The role of over diagnosis and reclassification in the marked increase of esophageal adenocarcinoma incidence. Journal of National Cancer Institute. January 19, 2005;97(2):142-6. 202.
What is the maximum permissible dose equivalent to an embryo or fetus that is allowed during a radiation worker's entire pregnancy? A. B. C. D.
00.5 mSv 01.0 mSv 05.0 mSv 10 mSv
Correct answer is C. RATIONALE: The NRC Title 10, which applies to organizations that receive a license from the NRC to use radioactive materials or operate nuclear facilities, stipulates that the dose equivalent to the embryo/fetus during an entire pregnancy, due to the occupational exposure of a declared pregnant woman, should not exceed 5 mSv. (Similarly, NCRP Report 116 recommends a monthly limit of 0.5 mSv to the embryo/fetus once pregnancy is declared.) REFERENCES: NRC Title 10, Code of Federal Regulations (US NRC 10 CFR §20.1208). NCRP Report 116. 203.
What is the expected risk of cancer recurrence in a patient with a 10-cm stage IA dysgerminoma of the ovary managed by unilateral salpingo-oophorectomy and no further treatment? A. B. C. D.
05% to 10% 15% to 25% 30% to 50% 75% to 85%
Correct answer is B. RATIONALE: This point is emphasized since many clinicians feel that a patient with a well-staged stage IA dysgerminoma can be observed after unilateral salpingooophorectomy, regardless of the size of the primary tumor, if fertility preservation is desired. Careful follow-up is required, because as many as 15% to 25% of patients will experience a recurrence (pooled data). Traditionally, most of these women received radiation. Current thinking is that because of the tumor's chemosensitivity, virtually all patients with a recurrence of dysgerminoma can be successfully salvaged if adequate follow-up and early detection can be accomplished.
204.
A craniospinal axis treatment requires a compensator for the spinal field. The field width is 8.0 cm on the patient's skin at 130-cm SSD, and the compensator tray is at 67 cm. What should be the minimum field width for the compensator? A. B. C. D.
04.1 cm 05.4 cm 06.2 cm 10.4 cm
Correct answer is A. RATIONALE: By performing a similar triangles calculation, the width of 8 cm is reduced by the ratio of 67/130. 205. Which of the following environmental exposures is a risk factor for the development of leukemia? A. B. C. D.
Chlorine Benzene Bromine Radon
Correct answer is B. RATIONALE: It is important to be aware of risk factors for screening/counseling family members. 206.
Which of the following diagnoses is most appropriate for a 16-year-old patient who has Parinaud's syndrome and an elevated serum α-fetoprotein level? A. B. C. D.
Hepatoblastoma Pineal germ cell tumor Hypothalamic germinoma Choriocarcinoma
Correct answer is B. RATIONALE: Parinaud's syndrome is an upward gaze palsy that can be caused by a pineal tumor. An elevated α-fetoprotein (AFP) level is suggestive of a germ cell tumor, particularly a non-germinomatous germ cell tumor. 207.
Based on the Massachusetts General Hospital (DeLaney) trial, what is the 5-year local control rate after radiation therapy is administered to patients with soft tissue sarcoma and positive margins after wide excision? A. B. C. D.
76% 54% 33% 12%
Correct answer is A. RATIONALE: This large retrospective study showed an overall 5-year local control rate of 76% in patients with soft tissue sarcoma and positive margins treated with excision and irradiation. REFERENCE: DeLaney, et al. International Journal of Radiation Oncology, Biology, and Physics (IJROBP). 2007;67:1460.
208.
The Laws of Bergonié and Tribondeau state that normal tissues should be radiosensitive if they contain a significant proportion of cells that are: A. B. C. D.
undifferentiated, with a low mitotic rate and a short mitotic future. undifferentiated, with a high mitotic rate and a long mitotic future. well differentiated, with a low mitotic rate and a short mitotic future. well differentiated, with a high mitotic rate and a long mitotic future.
Correct answer is B. RATIONALE: In the early days of radiation therapy (1906), two French radiobiologists, Drs. Bergonié and Tribondeau, attempted to categorize tissues with respect to their relative radiation sensitivities based on the proliferative and differentiation status of critical cells within those tissues. Those tissues found to be enriched in relatively undifferentiated cells with high proliferative potential and long proliferative life spans were considered to be the most "radiosensitive" (preferred term by today's standards would be "radioresponsive"). REFERENCE: Mettler and Upton. Medical Effects of Ionizing Radiation. 3rd edition, Chapter 1 (section on “Radiation Effects on Cell and Organ Systems”). 209.
What percent of patients diagnosed with primary ocular lymphoma will have CNS involvement within 1 year of diagnosis? A. B. C. D.
05% to 10% 20% to 30% 50% to 80% >90%
Correct answer is C. RATIONALE: Fifty to eighty percent of patients with primary ocular lymphoma will have CNS involvement at a median rate of 9 months. Thus, radiation therapy must include the intracranial contents and both eyes to ensure coverage of high-risk areas. 210.
Which of the following statements about proton radiation therapy is true? A. B. C. D.
Like photons, protons primarily interact via Compton interactions. Like photons, protons may be produced with an electron linear accelerator. Protons deliver their highest dose at the end of their range. Protons have a significantly higher LET than photons.
Correct answer is C. RATIONALE: Unlike photons, protons have a finite range in a medium (Braggs peak). As such, proton therapy may be delivered such that the maximum energy loss of the protons is delivered at the depth of the tumor, minimizing the dose to healthy tissue. Option A is false because protons primarily interact via ionization. Although protons may be accelerated with a linear accelerator (linac), option B is incorrect because they would not be accelerated with an electron linac, but rather with a proton or deuteron linear accelerator. Lastly, option D is incorrect because the LET of protons is similar to that of photons. 211.
Which of the following histologies of thyroid cancer is most likely to take up iodine? A. B. C. D.
Hürthle cell carcinoma Tall cell variant of papillary carcinoma Anaplastic carcinoma Follicular carcinoma
Correct answer is D. RATIONALE: It is very important to determine which histologies are likely to take up iodine so appropriate treatment can be initiated.
212.
A patient has anaplastic ependymoma with negative findings on CSF cytology and MRI of the spine. What is the risk of CNS dissemination after gross total resection, followed by radiation therapy to the primary site only? A. B. C. D.
<5% 10% to 15% 30% to 40% 50% to 60%
Correct answer is B. RATIONALE: Although anaplastic histology was once considered an indication for elective craniospinal radiation therapy (RT), the true risk of dissemination is very modest (~10-15%) if the primary site is treated locally. 213.
For most biological endpoints, which of the following statements best describes the relationship between RBE and LET? A. B. C. D.
RBE increases as LET increases. RBE decreases as LET increases. RBE reaches a maximum value near LET =100 keV/μm. RBE reaches a minimum value near LET =100 keV/μm.
Correct answer is C. RATIONALE: A graph of the relationship between RBE and LET is generally bell-shaped, with the RBE increasing to a maximum at an LET of approximately 100 keV/µm and then decreasing with further increase in LET. REFERENCE: Hall and Giaccia. Radiobiology for the Radiologist. 6th edition, Chapter 7 (Figures 7.6 and 7.7). 214.
Which of the following disease states is included in the intergroup rhabdomyosarcoma study (IRS) clinical group III classification? A. Localized tumor with resected positive lymph nodes with microscopic residual disease B. Localized or locally extensive disease with gross residual disease after a biopsy C. Localized disease with infiltration from the organ of origin to an adjacent structure with complete resection D. Distant metastatic disease present at diagnosis
Correct answer is B. RATIONALE: The IRS clinical group staging system refers to the extent of disease, degree of resection, and the presence or absence of involved lymph nodes and/or metastasis; whereas the TNM staging classification relies on the primary anatomic site first, then on size of the primary disease, invasiveness of the primary disease, and presence or absence of involved lymph nodes and/or metastasis. 215.
Which of the following treatments would be most appropriate for a 50-year-old patient who has Graves' disease with significant bilateral ophthalmopathy and diplopia? A. 131I therapy B. 40 Gy of fractionated radiation therapy to the orbits C. 20 Gy of fractionated radiation therapy to the orbits D. Systemic iodine chelation with immunosuppressive therapy
Correct answer is C. RATIONALE: Graves' ophthalmopathy can be treated with surgical decompression, steroid treatment, or low-dose fractionated radiation therapy (20 Gy in 10 to 20 fractions) with a reasonable symptomatic improvement. Four randomized trials with radiation therapy (RT) vs sham RT showed consistent marginal benefit.
216.
According to AAPM TG 40, an independent monitor unit calculation of a treatment plan should differ by no more than: A. B. C. D.
02%. 05%. 10%. undefined.
Correct answer is B. RATIONALE: According to AAPM TG 40, the independent calculation should not differ by more than 5% from the treatment plan. 217.
Which of the following visual-field defects is typically found in patients with craniopharyngioma? A. B. C. D.
Central scotoma Homonymous hemianopsia Bitemporal hemianopsia "Pie-in-the-sky" defect
Correct answer is C. RATIONALE: Bitemporal hemianopsia is the most common visual-field deficit noted because of compression of the optic chiasm. 218.
According to the PORTEC (Creutzberg) adjuvant endometrial trial, what percent of local failures was limited to the vagina? A. B. C. D.
90% to 100% 70% to 80% 50% to 60% 30% to 40%
Correct answer is B. RATIONALE: Seventy-three percent of local failures were in the vagina. This pattern of failure supports the rationale for using vaginal brachytherapy as adjuvant treatment. REFERENCE: Creutzberg CL, van Putten WL, Koper PC, et al. Surgery and postoperative radiotherapy versus surgery alone for patients with stage I endometrial carcinoma: Multicenter randomized trial. PORTEC Study Group. 219.
Which of the following radiation doses is most appropriate for treatment of a solitary plasmacytoma involving the femur? A. B. C. D.
25 Gy 36 Gy 45 Gy 60 Gy
Correct answer is C. RATIONALE: It is important to know that the radiation dose for solitary plasmacytoma of the femur is higher than that for myeloma. The content of this item is somewhat controversial, since some may chose to use 36 Gy for treatment based on a more recent analysis. However, the weight of the evidence supports the dose chosen (i.e., >40 Gy).
220.
Which of the following statements about radiation carcinogenesis is true? A. Radiation carcinogenesis is a deterministic effect. B. The probability of radiation carcinogenesis increases with increasing dose above a practical threshold of 500 mSv. C. IMRT has the potential to reduce the risk of secondary cancers due to less low-dose scatter to normal tissues. D. Proton radiation therapy has the potential to reduce the risk of secondary cancers due to the lack of an exit dose.
Correct answer is D. RATIONALE: In theory, proton radiation therapy has the potential to reduce the risk of second cancers because less normal tissue is irradiated due to the lack of an exit dose. It is important to bear in mind that radiation carcinogenesis is considered a stochastic effect (not a deterministic one); therefore, there is no radiation dose, no matter how small, that does not have some probability of causing a new cancer in previously irradiated normal tissue. 221.
Assuming that total white blood cell (WBC) counts follow a normal distribution, what would be the range of WBC counts for 50% of the individuals if the mean total WBC count is 7600 cells/mm3 with a standard deviation of 1400 cells/mm3? A. B. C. D.
Between 6200 and 9000 Between 7400 and 7800 <6200 and >9000 <7600
Correct answer is D. RATIONALE: Since the WBC counts follow a normal distribution, 50% of the population would be at or below the mean. 222.
What is the fundamental characteristic of a sliding-window IMRT? A. B. C. D.
The physical compensator is slid into position. The beam is on while the multileaf collimator leaves are moving. The x-ray target is sliding while the beam is on. The beam is on as the collimator is rotating.
Correct answer is B. RATIONALE: According to its definition, multileaf collimator (MLC) leaves move continuously while the beam is on for a given treatment field in a sliding-window or dynamic MLC IMRT. Although option A is a valid IMRT technique, it is not characteristic of a sliding-window IMRT. Neither options C or D are currently used techniques for delivering IMRT treatment plans.
223.
Which of the following immunohistochemical staining patterns differentiates primary bronchogenic carcinoma from metastatic adenocarcinoma of gastrointestinal origin? A. The expression of CDX2 is highly specific for pulmonary adenocarcinoma. B. The expression of TTF-1 is important in distinguishing primary bronchogenic carcinoma from metastatic adenocarcinoma. C. The expression of CK7− and CK20+ usually is associated with pulmonary adenocarcinoma. D. The expression of CK7+ and CK20− usually is associated with metastatic adenocarcinoma of the colorectum.
Correct answer is B. RATIONALE: It is important to know some principles of lung cancer pathology. CDX2 is highly specific for gastrointestinal malignancies, which could help distinguish from primary lung adenocarcinoma. The majority of primary lung carcinomas are positive for TTF-1, whereas metastatic adenocarcinoma to the lung is virtually always negative. Primary lung adenocarcinoma is usually CK7+ and CK20-, therefore distinguishable from CK7and CK20+ metastatic colorectal adenocarcinoma. 224.
Which of the following childhood CNS tumors has the worst prognosis? A. B. C. D.
Medulloblastoma Pilocytic astrocytoma Atypical teratoid rhabdoid tumor Pure germinoma
Correct answer is C. RATIONALE: Atypical teratoid rhabdoid tumor carries the worst prognosis among the tumors listed with a 1-year survival rate of 50%. The other tumors have a 5-year survival rate in the range of 80-90%. 225.
Under normal conditions, what are the dominant modes of DNA damage for γ-rays versus α-particles? A. B. C. D.
Direct action for both γ-rays and α-particles Direct action for γ-rays but indirect action for α-particles Indirect action for γ-rays but direct action for α-particles Indirect action for both γ-rays and α-particles
Correct answer is C. RATIONALE: The higher the LET of a radiation beam, the greater the fraction of cellular damage produced by direct action. For low-LET radiation, about 70% of the damage occurs through the indirect effect, barring cellular hypoxia or an unusually high concentration of radical scavengers.
226.
Which of the following factors is associated with an increased risk for the development of breast cancer? A. B. C. D.
Scattered fibroglandular breast tissue density on mammography History of unilateral clear nipple discharge on physical examination Twin pregnancy before 30 years of age Daily consumption of about 34 to 45 g of alcohol
Correct answer is D. RATIONALE: Mammographic density is an independent risk factor for breast cancer. B1-RADS reporting is related to mammographic sensitivity and is not an estimate of risk per se. A higher risk of subsequent beast cancer is associated with benign breast findings of proliferation without atypia (1.3–1.9 RR) and atypical ductal hyperplasia (3.9–13 RR). Unilateral clear nipple discharge is associated with ductal papillomas. Darker or blood-tinged nipple discharge is more commonly associated with breast cancer. Earlier age at first pregnancy and higher parity are associated with lower long-term risks for developing breast cancer. There is no association of an increased risk of breast cancer with twin pregnancies. Consumption of ~34–45 g of alcohol per day is associated with a 1.3 RR for breast cancer. REFERENCE: Harris, Lippman, Morrow, and Osborne. Diseases of the Breast. 3rd edition; 2004. 227.
Which of the following statements about tumors of the temporal bone is true? A. Paraganglioma is most common. B. Cranial nerve VIII is most commonly involved when skin cancer invades into the temporal bone. C. Level 2 lymph node involvement is most common when tumors involve the external auditory canal. D. The most frequent symptoms of temporal bone paragangliomas are headaches and facial nerve palsy.
Correct answer is A. RATIONALE: It is important to understand the spread pattern and common presentation of tumors in this area. The most frequent symptoms associated with temporal bone paragangliomas are hearing loss and tinnitus. 228.
Which of the following chromosomal translocations may identify patients with alveolar rhabdomyosarcoma associated with a very poor prognosis? A. B. C. D.
t(X;18) with SYT-SSX1 fusion transcript t(2;13) with PAX3-FKHR fusion transcript t(11;22) with EWS-FL1 fusion transcript t(9;22) with bcr-abl fusion transcript
Correct answer is B. RATIONALE: The t(2;13) with the PAX3-FKHR fusion transcript identified a group of patients in the IRS-IV study population who had a 4-year overall survival rate of <10%. The PAX7-FKHR transcript identified a group of patients who had alveolar rhabdomyosarcoma (RMS) and a better prognosis (i.e., a 4-year overall survival rate of >70%). These translocations and fusion transcripts are not identified in embryonal RMS. Option A is seen in synovial sarcoma. Option C is seen in Ewing's sarcoma, and option D is seen in chronic myelogenous leukemia (CML).
229.
Which of the following correction factors would be most important to apply when a dose calibration is performed? A. B. C. D.
Incomplete ion collection efficiency (Pion) Temperature pressure (PTP) Electrometer calibration (Pelec) Polarity effect (Ppol)
Correct answer is B. RATIONALE: Temperature-pressure correction factor (PTP) is dominating, and typically on the order of 3%. Other correction factors are typically about 1% or less. 230.
A randomized trial from the MRC Testicular Study Group compared irradiation to the paraaortic and pelvic lymph nodes versus to the paraaortic lymph nodes alone. Which of the following statements about this trial is true? A. B. C. D.
There was a statistically significant difference in overall survival. There was a statistically significant difference in relapse-free survival. There was no difference in the rate of azoospermia between the two groups. The pelvic failure rate was less than 5% in patients receiving radiation therapy to the paraaortic lymph nodes only.
Correct answer is D. RATIONALE: The pelvic failure rate in patients treated with paraaortic radiation only was less than 2%. 231.
Which of the following radiation treatments is most appropriate for a well-demarcated, round, 5-mm basal cell carcinoma of the lower eyelid that is 2 mm thick? A. 6-MeV electrons, no bolus, 1.5-cm circular field size B. 6-MeV electrons, intraorbital tungsten shield, 50 Gy in 25 fractions of 2 Gy over 5 weeks C. 100-kV x-rays, 0.5-cm bolus, 50 Gy in 25 fractions of 2 Gy over 5 weeks D. 100-kV x-rays, intraorbital tungsten shield, 54 Gy in 18 fractions of 3 Gy over 3.6 weeks
Correct answer is D. RATIONALE: Fewer and fewer residents are receiving experience treating skin tumors with 100 kV. Choice D works very well for the majority of skin lesions; choice A would need a bolus; choice B would need a ceramic (not tungsten) shield and is overly fractionated; choice C should not have a bolus and is overly fractionated. 232.
Which of the following pairs of DNA damaging agents and resulting DNA lesions are most responsible for cell death? A. B. C. D.
DNA Damaging Agent Paclitaxel Ionizing radiation Ultraviolet radiation Etoposide
DNA Lesion Interstrand crosslinks Single-strand breaks Pyrimidine dimers Bulky adducts
Correct answer is C. RATIONALE: DNA double-strand breaks represent the most dangerous type of DNA damage caused by ionizing radiation (and many chemotherapeutic drugs). A thorough understanding of the type of damage caused by radiation and different chemotherapeutic agents is important for the rational application of existing combination therapies, and would be essential when testing novel molecular therapies that target DNA repair processes in cancer cells.
233.
According to the Lung Intergroup 0139 trial, the mortality rate was highest after which of the following surgical procedures for stage III NSCLC? A. B. C. D.
Right-sided pneumonectomy Left-sided pneumonectomy Left lower lobectomy Right upper lobectomy
Correct answer is A. RATIONALE: The mortality rate in patients receiving trimodality treatment was 7.9%, and the mortality rate in patients receiving chemoradiation was 2.1%. Complex pneumonectomy had a much higher mortality rate than that of simple pneumonectomy. The mortality rate after right-sided complex pneumonectomy was 50%; the mortality rate after leftsided complex pneumonectomy was 16%. The mortality rate for lobectomy was 1%, which increased to 26% after pneumonectomy. 234.
As determined by the planning optimization, IMRT plans are significantly more conformal than 3D plans because the: A. B. C. D.
number of gantry angles used has decreased. collimator is rotated. wedges are inverted for several of the fields in IMRT. beam fluence is nonuniform.
Correct answer is D. RATIONALE: IMRT uses nonuniform beam intensities across a radiation field to tightly conform to a target of interest. There are several techniques available to achieve this end goal. 235.
Which of the following dose fractionation schemes is most appropriate for patients with stage I seminoma? A. B. C. D.
25 Gy in 20 fractions 30 Gy in 10 fractions 36 Gy in 20 fractions 45 Gy in 25 fractions
Correct answer is A. RATIONALE: As discussed in Gunderson's text, 25 Gy in 20 fractions is one of fractionation schemes used at Princess Margaret Hospital. Other fractionation schemes described here are incorrect. 236.
Which of the following statements about the treatment of paraganglioma is true? A. B. C. D.
A radiation dose of 45 Gy should offer a local control rate of >80%. A complete response is common following external-beam radiation therapy. Stereotactic radiosurgery is contraindicated. Regional lymph nodes should be electively irradiated.
Correct answer is A. RATIONALE: It is important to understand the effect of treatment, the appropriate dose, and volume for this very curable benign tumor. Local control rates with external-beam radiation were reported ranging from 65% to 100% with a mean of 90%. However, a complete response is uncommon. Most patients will have stable disease after radiation therapy. Stereotactic radiosurgery has been used in the primary treatment of paragangliomas with a dose ranging from 12 to 18 Gy. Lymph node metastasis is extremely rare for paragangliomas.
237.
Which of the following findings on MR spectroscopy is most commonly associated with a low-grade astrocytoma? A. B. C. D.
Low choline Low N-acetylaspartate High creatine High lactate
Correct answer is B. RATIONALE: Patients with low-grade astrocytoma typically have low Nacetylaspartate (NAA), choline/creatine>1, and no lactate. 238.
Based on an understanding of thermal dose and the effects of timing between heat and radiation, which of the following protocols would be expected to produce the greatest thermal enhancement ratio? A. B. C. D.
Heat prior to radiation Heat following radiation Heat alternating with radiation daily Heat concurrent with radiation
Correct answer is D. RATIONALE: For the combination of heat and radiation, the greatest thermal enhancement ratio (TER) occurs when the two agents are given simultaneously. For moderately elevated temperatures that do not in and of themselves cause much heat-induced cell killing, hyperthermia has been shown to interfere with the repair of radiation-induced DNA damage and results in a reduction in the shoulder on the radiation survival curve when the two agents are administered either simultaneously or within minutes of each other. This has also been demonstrated in vivo in rodent tumors, where TER’s of nearly 5.0 have been achieved for the combination treatment relative to radiation alone. Although heat can also sensitize normal tissues to radiation injury, generally there is still a net therapeutic gain because normal tissues are better equipped physiologically to dissipate heat relative to tumors. Therefore, the sustained elevated temperatures needed to result in radiosensitization are less likely to occur. REFERENCE: Hall and Giaccia. Radiobiology for the Radiologist. 6th edition, Chapter 28. 239.
An increased risk of hepatocellular carcinoma is associated with exposure to: A. B. C. D.
hepatitis A. Helicobacter pylori. human papillomavirus. aflatoxin B1.
Correct answer is D. RATIONALE: Aflatoxin B1 has been associated with an increased risk of hepatocellular carcinoma (HCC). Hepatitis B and C (not hepatitis A) are associated with an increased risk of HCC.
240.
Which of the following AJCC stage groups is associated with a 2.5-cm squamous cell carcinoma of the vulva with bilateral inguinal lymph node metastases and no evidence of metastatic disease? A. B. C. D.
IIIA IIIB IVA IVB
Correct answer is C. RATIONALE: T2N2M0 is Stage IVA. IVB represents distant metastatic disease. REFERENCE: AJCC Cancer Staging Manual, 6th edition. 241.
Which of the following factors is associated with the international prognostic score (IPS) for Hodgkin lymphoma? A. B. C. D.
Extranodal site Performance status Erythrocyte sedimentation rate Serum albumin level
Correct answer is D. RATIONALE: A serum albumin level of <4 g/dL is the only factor belonging to the international prognostic score for Hodgkin lymphoma. REFERENCE: HasenClever, et al. New England Journal of Medicine (NEJM). 1998;1506-14. 242.
Which of the following thoracic radiation therapy regimens administered concurrently with chemotherapy improves overall survival for limited-stage SCLC? A. 45 Gy in twice-daily fractions of 1.5 Gy each B. 48 Gy in twice-daily fractions of 1.5 Gy each, with a 2-week break after 24 Gy C. 61.2 Gy in once-daily fractions of 1.8 Gy each for 5 weeks and twice-daily fractions of 1.8 Gy each for the last 9 days D. 70 Gy in once-daily fractions of 2 Gy each
Correct answer is A. RATIONALE: The radiation therapy regimen of 45 Gy bid is the only one showing a survival benefit in a randomized Phase III trial. REFERENCE: Turrisi. Intergroup trial. New England Journal of Medicine (NEJM). January 28, 1999;340(4):265-71. 243.
For a pediatric patient receiving craniospinal irradiation, the advantage of using electrons versus photons to treat the posterior spinal fields is to: A. B. C. D.
provide improved coverage of the spine. minimize hot spots between the abutting cranial and spinal fields. minimize the exit dose. minimize the surface dose.
Correct answer is C. RATIONALE: Compared to photons, electrons are less penetrating. As a result, the dose to structures anterior to the spine is considerably lower when electrons are used for spinal irradiation.
244.
The cervix drains primarily into which of the following lymph nodes? A. B. C. D.
Paracervical Internal iliac External iliac Inguinal
Correct answer is A. RATIONALE: The uterine cervix has abundant lymphatic drainage primarily into the paracervical lymph nodes; from there, drainage is to the external and internal iliac nodes and subsequently to the common iliac and paraortic lymph nodes. Drainage of the uterine fundus, in contrast, is to the external and internal iliac nodes as well as directly into the paraortic lymph nodes. 245.
A person receiving 8 to 12 Sv of acute radiation exposure most likely will die of which of the following syndromes? A. B. C. D.
Prodromal Hematopoietic Gastrointestinal Cerebrovascular
Correct answer is C. RATIONALE: The mode of death most associated with an acute exposure in the 8-12 Sv range is the gastrointestinal syndrome, which is precipitated by radiation-induced killing of "crypt cells" (stem cells of the gut lining). Death typically occurs within a week of irradiation. The irradiated individual likely exhibited the prodromal syndrome as well (not fatal per se) and would also have developed the hematopoietic syndrome within a few weeks of irradiation; however, death from the GI syndrome would occur sooner. The dose range specified was below the threshold for the development of the cerebrovascular syndrome, however. REFERENCE: Hall and Giaccia. Radiobiology for the Radiologist. 6th edition, Chapter 8. 246.
Which of the following complications most commonly occurs in patients receiving fractionated radiation therapy for pituitary adenomas? A. B. C. D.
Vascular injury Optic neuropathy Radiation necrosis Endocrine dysfunction
Correct answer is D. RATIONALE: The majority of patients with pituitary adenomas develop one or many endocrine deficiencies after undergoing radiation therapy. 247.
The dose rate at the isocenter of a megavoltage linear accelerator is 4 Gy/min. The dose rate 1 cm from a typical HDR 192Ir source is about: A. B. C. D.
1000 times greater. 1000 times less. the same. the square root of 192.
Correct answer is C. RATIONALE: The activity of a typical high-dose-rate (HDR) 192Ir source is 5 to 10 Ci, and the dose rate is about 3 to 8 Gy/min.
248.
Which of the following statements about preinvasive breast cancer findings is true? A. The histology of invasive cancer is usually lobular in patients with LCIS. B. LCIS is not associated with any clinical or mammographic abnormalities. C. In the NSABP P1 trial, the use of tamoxifen for patients with LCIS did not reduce the incidence of breast cancer. D. There is a slightly higher rate of ipsilateral breast tumor recurrence when LCIS is associated with primary invasive cancer.
Correct answer is B. RATIONALE: In the tamoxifen prevention trial, 18/411 women in the placebo group and 8/415 women in the tamoxifen group had breast recurrences in the setting of LCIS only. This resulted in a 56% reduction in risk. However, because the number of events was so small, it did not reach statistical significance. When invasive cancer occurs in the setting of LCIS, the histology is usually ductal. There is no difference in IBTR when LCIS is associated with the primary invasive cancer. REFERENCES: Fischer.Tamoxifen for prevention of breast cancer: report of the NSABP P-1 study. Journal of the National Cancer Institute. 1998;90:13711388. Harris, Lippman, Morrow, and Osborne, Diseases of the Breast. 3rd edition, 2004;497505. 249.
Which of the following pairs of tumor markers should be obtained to evaluate a patient with a germ cell tumor of the ovary? A. B. C. D.
CA-125 and CA-130 CA-19-9 and CA-125 CEA and CA-15-3 AFP and β-hCG
Correct answer is D. RATIONALE: AFP and β-hCG are tumor markers in germ cell tumors of the ovary. AFP will be elevated in tumors with yolk sac elements, and β-hCG will be elevated in tumors with chorionic elements. CA-125 is commonly used as a marker for epithelial ovarian cancers; however, CA-130 may be elevated in more than 90% of women with epithelial ovarian cancers. CA-19-9 is often elevated in mucinous cancers of the ovary. CA-19-9 has been combined with CA-125 as markers for borderline tumors of the ovary. CA-15-3 is elevated in about one half of women with ovarian cancer, but it is not useful on its own. When CA-15-3 is used in conjunction with the CA-125 assay, it increases the specificity in the differential diagnosis of adnexal masses. 250.
A "reciprocal dose plot" type of isoeffect curve is used to calculate a tissue's: A. B. C. D.
Tpot.
α/β ratio.
repair half-time. growth fraction.
Correct answer is B. RATIONALE: The reciprocal dose plot technique pioneered by Douglas and Fowler (in which the reciprocal of the total radiation dose to achieve an isoeffective level of tissue response is plotted as a function of the dose per fraction) is used to determine a tissue’s α/β ratio. REFERENCE: Douglas BC and Fowler JF. Radiation Research Journal. 1976;66:401426.
251.
Which of the following types of non-Hodgkin lymphoma is most aggressive? A. B. C. D.
Mycosis fungoides Mantle cell Extranodal marginal zone B-cell Grades I and II follicular
Correct answer is B. RATIONALE: Mantle cell lymphoma is mostly diagnosed as stage IV disease and is known to have a moderately aggressive course with median survival around 3 years. Follicular, extranodal marginal zone, and mycosis fungoides all have an indolent disease course. REFERENCE: DeVita. 252.
What was the impact on the 4-year actuarial survival in patients receiving chemotherapy, according to the Phase III (SWOG 8797, Peters) trial comparing postoperative pelvic irradiation alone versus chemoradiation in high-risk patients with cervical cancer? A. B. C. D.
Worse Comparable Better Survival was not reported.
Correct answer is C. RATIONALE: SWOG Trial 8797 compared adjuvant pelvic irradiation versus adjuvant chemoradiotherapy in high-risk cervical cancer patients following radical hysterectomy. High-risk features included pelvic lymph node involvement, positive surgical margins, and microscopic parametrial involvement. Patients receiving pelvic irradiation plus chemotherapy had an improved 4-year actuarial survival (81% vs 71%) compared to those treated with adjuvant irradiation alone. REFERENCE: Peters, et al. Journal of Clinical Oncology. 2000;18:1606-1613. 253.
Which of the following outcomes is associated with patients who have breast cancer that has metastasized to multiple tissue sites with or without bone involvement? A. Median survival is 4.8 years. B. Overall survival is improved with chemotherapy. C. Patients with ER-negative and PR-positive tumors have a 10% to 20% response rate to endocrine therapy alone. D. Patients with ER-positive and PR-positive tumors have a 50% to 75% response rate to endocrine therapy alone.
Correct answer is D. RATIONALE: Median survival for patients with metastatic breast cancer is 2½ to 3 years. TUMOR ER PR Negative Negative Positive Negative Negative Positive Positive Positive
RESPONSE RATE TO ENDOCRINE THERAPY <10% 20%–30% 30%–50% 50%–75%
REFERENCE: Harris JR, Lippman ME, Morrow M, and Osborne CK. Treatment of metastatic breast cancer. Diseases of the Breast. 3rd edition. 2004;1101-1159.
254.
A 10 x 10-cm2 10-MV photon beam is prescribed to a point at a depth of 10 cm in the mediastinum with no heterogeneity. Using heterogeneity dose corrections in which the same beam traverses 6 cm of the lung, the dose at this point becomes: A. B. C. D.
12% higher. 06% higher. 06% lower. 12% lower.
Correct answer is A. RATIONALE: A simple calculation would use the fact that the 6 cm of lung is equivalent to ~2 cm of tissue (deff = density lung x distance = 0.3 x 6 cm = 1.8 cm), thereby 4 cm of increased transmission. Based on 3% per cm, a 12% higher dose would be received. 255.
Which of the following dose ranges of EBRT is most appropriate for an adult patient who has undergone resection with negative surgical margins for soft tissue sarcoma of the extremity? A. B. C. D.
68 to 70 Gy 60 to 66 Gy 55 to 59 Gy 45 to 50 Gy
Correct answer is B. RATIONALE: The most appropriate postoperative radiation dose is in the range of 60 to 66 Gy. 256.
Which of the following tests should be used in the analysis of a nominal independent variable with a nominal dependent variable? A. B. C. D.
Chi-square One-way ANOVA Regression t test
Correct answer is A. RATIONALE: For questions involving two variables (independent/dependent), the appropriate method is as follows: Chi-square: nominal/nominal. One-way ANOVA: nominal (more than two values)/numerical. Regression: numerical/numerical. t test: nominal (binary)/numerical. Actuarial: nominal/numerical (censored).
257.
Which of the following is NOT implicated in the mechanism of action of tirapazamine? A. B. C. D.
Generation of an oxidizing free radical Generation of hydrogen peroxide Interference with DNA replication Poisoning of topoisomerase II
Correct answer: ABCD. RATIONALE: Tirapazamine is a heteroaromatic N-oxide that undergoes a one-electron reduction in the absence of oxygen to form a short-lived oxidizing free radical intermediate. This toxic species is thought to be responsible, directly or indirectly, for the production of DNA double-strand breaks, interference with DNA replication and poisoning of topoisomerase II, one or more of which can result in cell death. Tirapazamine is a substrate for classic one-electron reductases such as cytochrome P450 and P450R, and NOS, nitric oxide synthase. REFERENCES: Hall and Giaccia. Radiobiology for the Radiologist. 6th edition, Chapter 25. Wardman P. Chemical radiosensitizers for use in radiotherapy. Clinical Oncology. 2007;19:397-417. McKeown SR, Cowen RL, and Williams KJ. Bioreductive drugs: From concept to clinic. Clinical Oncology. 2007;19:427-442. 258.
The RTOG 91-11 trial showed that concurrent chemoradiation: A. B. C. D.
increased severe late toxicity compared to radiation therapy alone. increased local control by approximately 20% compared to radiation therapy alone. had an equal larynx preservation rate compared to sequential chemoradiation. had the same rate of mucositis compared to sequential chemoradiation.
Correct answer is B. RATIONALE: Concurrent chemoradiation is more effective than radiation therapy (RT) alone in preserving the larynx (approximately 78% vs 56% at 2 years). It is important for radiation oncologists to appreciate the relative magnitude of this improvement. Also, this trial is unique in showing an effect of concurrent chemoradiation on distant metastases. 259.
Considering the typical percent depth dose curves for electron beams, the surface dose for a 9-MeV beam is in what percentage range of the maximum absorbed dose, dmax? A. B. C. D.
20% to 39% 40% to 59% 60% to 79% 80% to 100%
Correct answer is D. RATIONALE: Unlike photons, skin sparing is modest at best. The typical surface dose for megavoltage electron beams ranges from 80% to 100% of the dose at dmax. 260.
Which of the following histologies is most commonly associated with primary CNS lymphoma? A. B. C. D.
Mantle cell Large B-cell Anaplastic Follicular
Correct answer is B. RATIONALE: Large B-cell lymphoma is the most common histology for CNS lymphoma. REFERENCE: DeVita VT, Hellman S, Rosenberg SA. Cancer: Principles & Practice of Oncology. 6th edition. Lippincott, Philadelphia; 2001;2300.
261.
Overall survival in patients with locally advanced prostate cancer has been shown to be increased by EBRT: A. B. C. D.
combined with a brachytherapy boost. combined with hormone therapy. administered to the whole pelvis. administered via dose escalation.
Correct answer is B. RATIONALE: Combining hormone therapy with external-beam radiation therapy (EBRT) is the only choice that has been shown to increase overall survival. 262.
The interfraction interval is typically no less than 6 hours for radiation therapy delivered in multiple dose fractions per day. The radiobiological reason for this treatment protocol is to: A. allow reoxygenation to occur in tumors. B. cause tumor cells to undergo cell cycle redistribution into more radiosensitive phases. C. take maximum advantage of cellular repopulation in normal tissues. D. take maximum advantage of repair of SLD in late-responding normal tissues.
Correct answer is D. RATIONALE: In several seminal hyperfractionation trials, most notably the CHART trial for head and neck cancer, multiple doses per day delivered in less than 6-hour intervals led to some unanticipated cases of radiation myelitis. This has been interpreted as being a manifestation of the “incomplete repair” of sublethal damage. Late-responding normal tissues have somewhat longer half-times of repair than early-responding tissues; therefore, they may require a longer interfraction interval before this repair is complete. In fact, it has been suggested by some that even 6 hours between fractions may be inadequate to take maximum advantage of the sparing effect of sublethal damage repair in the spinal cord and brain. REFERENCE: Dische, et al. Radiotherapy and Oncology: Journal of the European Society for Therapeutic Radiology and Oncology. 1997;44:123-136. 263.
What is the expected rate of CNS metastasis after systemic chemotherapy and PCI for patients with extensive-stage SCLC? A. B. C. D.
05% 15% 30% 50%
Correct answer is B. RATIONALE: The incidence of brain metastases in patients who had extensive-stage SCLC and received PCI was 15%. The incidence of brain metastases in patients who had limited-stage SCLC and received PCI was approximately 20%.
264.
What is the most common histology associated with malignant tumors of the ureters in the United States? A. B. C. D.
Squamous cell carcinoma Transitional cell carcinoma Small cell carcinoma Adenocarcinoma
Correct answer is B. RATIONALE: Transitional cell carcinoma is the most common histology for ureteral carcinomas. 265.
Which of the following doses of definitive radiation therapy is most appropriate for a patient with unresectable Ewing's sarcoma of the pelvis? A. B. C. D.
70.0 Gy 64.8 Gy 55.8 Gy 50.4 Gy
Correct answer is C. RATIONALE: The recommended radiation dose for gross disease in a patient with Ewing's sarcoma of the pelvis is 55.8 Gy. 266.
Which of the following stages would be most appropriate for a patient who has Wilms tumor with diffuse tumor spillage into the abdominal cavity? A. B. C. D.
I II III IV
Correct answer is C. RATIONALE: This is the definition of stage III disease: Residual intraabdominal tumor (nonhematogenous) exists after the completion of surgery. Lymph node findings are positive, or peritoneal implants are found. The resected specimen has histologically positive margins, or the tumor has spilled into the abdominal cavity. 267.
How many mrem is equal to 1 mSv? A. B. C. D.
000.1 001.0 010 100
Correct answer is D. RATIONALE: There is a direct conversion from conventional units (mrem) to SI units (mSv), where 100 rem = 1 Sv.
268.
What is the number of degrees of freedom in a Chi-square test for the equality of proportions from three independent populations? A. B. C. D.
2 3 4 5
Correct answer is A. RATIONALE: The number of degrees of freedom is the number of groups minus 1. 269.
Which of the following is a cellular feature of necrosis? A. B. C. D.
Cytoplasmic shrinkage Chromatin condensation Mitochondrial swelling Membrane blebbing
Correct answer is C. RATIONALE: Mitochondrial swelling (along with overall cellular swelling, culminating in the release of intracellular material into the surrounding microenvironment) is a defining characteristic of a cell undergoing necrosis. Cytoplasmic shrinkage, chromatin condensation, and membrane blebbing are distinguishing features of apoptosis (not necrosis). 270.
According to the 1999 Intergroup (Turrisi) trial, accelerated hyperfractionated thoracic radiation therapy beginning with the first cycle of chemotherapy significantly improved 5-year survival as compared with concurrent once-daily radiation therapy by: A. B. C. D.
30%. 20%. 10%. 05%.
Correct answer is C. RATIONALE: The survival rates for patients receiving once-daily radiation therapy were 41% at 2 years and 16% at 5 years. REFERENCE: New England Journal of Medicine. Jan 28, 1999;340(4):265-71.
271.
According to a 2008 study by the University of Pennsylvania, the use of breast MRI for the initial diagnosis and pretreatment evaluation of patients with early-stage breast cancer demonstrated which of the following conclusions? A. It has a greater positive predictive value than mammogram or ultrasound alone in the selection of patients for partial breast irradiation. B. It has a greater positive predictive value for detecting multicentric disease in patients with invasive breast cancer than in those with noninvasive breast cancer. C. It is not associated with an improvement in outcome after breast-conserving surgery and radiation therapy. D. It should be used for initial staging of women who have breast cancer associated with BRCA1 and BRCA2 germline mutations.
Correct answer is C. RATIONALE: This was a retrospective study of patients treated by breast-conserving surgery and radiation therapy. The primary endpoint was comparison of outcomes between women who either had a breast MRI as part of their initial pretreatment evaluation or did not. There were no differences in local control or survival outcomes. The study did not generate data or make conclusions about the appropriateness of breast MRI in different subgroups for selecting patients for breast-conserving surgery or partial breast irradiation. REFERENCE: Solin, et al. Journal of Clinical Oncology. 2008;26:386-91. 272.
Which of the following radiation doses and fractionation schemes would be most appropriate for a 3-year-old child who has orbital embryonal rhabdomyosarcoma with gross disease? A. B. C. D.
36 Gy delivered in 1.8-Gy fractionation daily 45 Gy delivered in 1.8-Gy fractionation daily 50.4 Gy delivered in 1.8-Gy fractionation daily 59.4 Gy delivered in 1.1-Gy fractionation twice daily
Correct answer is B. RATIONALE: The current recommendation is 45 Gy given in 25 fractions of 1.8 Gy with a 5-year overall survival (OS) rate of 96%, and a 5-year failure-free survival (FFS) rate of 89% based on IRS III data. 273.
According to the NRC, the annual total effective dose limit to an individual member of the general public is: A. B. C. D.
00.5 mSv. 01 mSv. 10 mSv. 50 mSv.
Correct answer is B. RATIONALE: According to 10 CFR 20.1301, the annual maximum dose limit to a member of the general public is 1 mSv. Exceptions can be made for caregivers and/or family members caring for a patient following a radioactive procedure. However, under these circumstances; the maximum annual dose is limited to 5 mSv.
274.
Which of the following statements concerning the oxygen enhancement ratio (OER) is true? A. It is higher when one or a few large radiation doses are used versus many smaller-sized dose fractions. B. It increases with increasing LET of the type of radiation used. C. For tissues characterized by a partial pressure of oxygen of 30 mm Hg, the OER is typically 2.5 to 3.0. D. The "paired survival curve" method is used to determine the OER.
Correct answer: ABCD. RATIONALE: Calculated values for the OER are typically higher (2.53.0) when a “severe” endpoint that involves a great deal of cell killing is used (such as might be achieved when a single, large radiation dose is given) than when many smaller dose fractions are used that produce less cell killing and a “milder” endpoint (OER ≈ 1.5-2.0). REFERENCE: Hall and Giaccia. Radiobiology for the Radiologist. 6th edition, Chapter 6. 275.
Which of the following statements about the prognosis of patients who have IBTR after breast-conserving therapy is true? A. Overall survival is not affected by the location of tumor recurrence in the breast. B. Axillary lymph node status of the primary tumor does not affect overall survival. C. Patients with BRCA1 or BRCA2 germline mutations have a worse prognosis than patients without these mutations. D. The histologic grade of the primary tumor affects the patient's prognosis.
Correct answer is D. RATIONALE: Overall survival is affected by the quadrant of recurrence, the histologic grade, and lymph node (LN) status of the primary tumor. Factors associated with the risk of distant metastases are the location of the recurrence, extent of local recurrence, lymph node status of the primary tumor, and histologic grade of the primary tumor. Excellent outcomes have been reported for patients with BRCA1/BRCA2 germline mutations after salvage treatment for ipsilateral breast tumor recurrence (IBTR). REFERENCES: Voogd AC. Local recurrence after breast-conserving therapy (BCT) for early stage-breast cancer detection, treatment, and outcome. Dutch Study Group on local recurrence after breast conservation. Cancer. 1999;89:437-446. Turner BC. BRCA1/BRCA2 Germline mutations in locally recurrent breast cancer patients after lumpectomy and radiation therapy; implications for breastconserving management in patients with BRCA1/BRCA2 mutations. Journal of Clinical Oncology. 1999;17:3017-3024. Pierce LJ. Effect of radiotherapy after breast-conserving treatment in women with breast cancer and germline BRCA1/2 mutations. Journal of Clinical Oncology. 2000;18:3360-3369.
276.
What is the expected 5-year overall survival rate for a 5-year-old patient who has average-risk medulloblastoma treated with craniospinal irradiation and chemotherapy? A. B. C. D.
67% 70% 85% 93%
Correct answer is C. RATIONALE: Children's cancer group study A9961 for average-risk medulloblastoma reported a 5-year-old child’s overall survival (OS) rate to be 86%, while a 5year-old child's event-free survival (EFS) rate was reported to be 81%. 277.
Which of the following toxicities is most common in patients who are receiving concurrent chemoradiation for NSCLC? A. B. C. D.
Pneumonitis Esophagitis Pericarditis Myelitis
Correct answer is B. RATIONALE: Esophagitis can be observed in 40% to 60% of patients receiving concurrent chemoradiation therapy. Pneumonitis is much less common. Pericarditis and myelitis are rare in the modern era of radiation therapy. 278.
Which of the following statements about the MAGIC (Cunningham) study comparing perioperative ECF chemotherapy to surgery alone for resected gastric cancer is true? A. A lower rate of curative surgery was demonstrated in patients who underwent perioperative chemotherapy. B. A higher rate of postoperative complications was found in patients who underwent perioperative chemotherapy. C. The overall and progression-free survival rate was improved in patients who underwent perioperative chemotherapy. D. Most patients completed all 6 cycles of chemotherapy.
Correct answer is C. RATIONALE: The MAGIC study showed a higher rate of curative surgery with chemotherapy, a similar postoperative complication rate, and improved overall survival (OS) rate and progression-free survival (PFS) rate. However, only 41% of patients completed all chemotherapy. REFERENCE: Cunningham, et al. New England Journal of Medicine (NEJM). 2006. 279.
How can the peripheral dose to a pregnant patient be eliminated? A. B. C. D.
Increasing secondary jaw thickness Using multileaf collimators and blocks simultaneously Placing special blocking immediately next to the patient The peripheral dose cannot be eliminated.
Correct answer is D. RATIONALE: Although peripheral dose may be reduced by placing special blocking immediately next to the patient, peripheral dose cannot be completely eliminated due to internal scatter.
280.
Which of the following types of biopsy is most commonly used to diagnose Hodgkin lymphoma? A. B. C. D.
Excisional Incisional Fine-needle aspirate Random
Correct answer is A. RATIONALE: Excisional biopsy is the preferred method of biopsy since it maintains architecture and sufficient material for immunohistochemistry flow cytometry. 281.
Which of the following statements about a radiation-induced stochastic effect is true? A. B. C. D.
The severity of the effect increases with dose. There is a threshold dose below which the risk of the effect is zero. Radiation-induced cataracts are an example of a stochastic effect. The probability of occurrence of the effect increases with dose.
Correct answer is D. RATIONALE: The definition of a stochastic radiation effect is one that is probabilistic in nature and whose incidence increases with increasing dose, is “all or nothing” (i.e., does not show degrees of severity), and is not characterized by a threshold dose below which the likelihood of the effect is zero. Non-stochastic, also called deterministic, effects show dose thresholds and graded levels of severity depending on dose. REFERENCE: Hall and Giaccia. Radiobiology for the Radiologist. 6th edition, Chapters 10, 14, and 15. 282.
Which of the following syndromes is associated with neuroblastoma? A. B. C. D.
Sick sinus syndrome Restless legs syndrome Opsomyoclonus-ataxia syndrome SIADH secretion
Correct answer is C. RATIONALE: Opsomyoclonus-ataxia syndrome is seen in 1.3% of patients who have neuroblastoma. 283.
Which of the following statements about the management of thymoma is true? A. B. C. D.
Chemotherapy is not effective. A complete thymectomy is preferred for resectable disease. Adjuvant radiation therapy is indicated for patients with Masaoka stage I disease. Preoperative radiation therapy is indicated for patients with Masaoka stage I disease.
Correct answer is B. RATIONALE: For resectable disease, a complete thymectomy is preferred because recurrences have been observed in the residual thymus after a partial thymectomy. Several reports showed that 17% to 28% of patients who have thymomas develop a second malignancy after thymectomy. Thus, close follow-up is needed given that secondary malignancy is common in patients with thymomas.
284.
Which of the following statements about the diagnosis of inflammatory breast cancer is true? A. B. C. D.
Dermal lymphatic invasion is classified as stage T4d. Dermal lymphatic invasion may be absent on a biopsy of the skin. Since inflammatory carcinoma is a clinical diagnosis, a biopsy is not required. Dermal involvement over more than one third of the breast is classified as stage T4d.
Correct answer is B. REFERENCE: American Joint Committee on Cancer (AJCC) staging, 6th edition. 285.
According to the EORTC 22911 (Bolla) trial, adjuvant radiation therapy after a radical prostatectomy is most beneficial for patients with: A. B. C. D.
a positive margin in the pathology specimen. a Gleason score of 4+5 in the pathology specimen. seminal vesicle involvement in the pathology specimen. a PSA level of 0.4 ng/mL immediately after the prostatectomy.
Correct answer is A. RATIONALE: In the randomized controlled European Organization for Research and Treatment of Cancer (EORTC) trial 22911, surgical margin status assessed by review of the pathology specimen was the strongest predictor of prolonged biochemical disease-free survival with immediate postoperative radiation therapy. 286.
Neutrons may interact within the medium they are traversing by which of the following mechanisms? A. B. C. D.
Bremsstrahlung Photoelectric effect Pair production Knockout reaction
Correct answer is D. RATIONALE: Unlike photons and charged particles, neutrons interact almost exclusively with the nucleus of an atom. Of the options listed, the only interaction possible for neutrons is the knockout reaction. Photons may interact via the photoelectric effect and pair production, and electrons passing near a nucleus may lose energy via the radiative emission of bremsstrahlung x-rays. 287.
Which of the following statements about the role of hypoxia in tumor progression is FALSE? A. B. C. D.
Cyclic hypoxia followed by reoxygenation can induce genomic instability. Low oxygen conditions increase the metastatic potential of tumor cells. Hypoxia can select for tumor cells that retain apoptotic pathways. Clinical studies have shown that tumor hypoxia has a negative impact on patient outcomes, even in the absence of radiation therapy.
Correct answer is C. RATIONALE: Hypoxia has been shown to select for genomically unstable tumor cells with mutations that result in diminished apoptotic potential. REFERENCE: Hall and Giaccia. Radiobiology for the Radiologist, 6th edition, Chapter 6.
288.
Which of the following factors best justifies the use of preoperative radiation therapy for a patient with inflammatory breast cancer? A. B. C. D.
Skin-sparing mastectomy Dermal lymphatic involvement Matted axillary lymph nodes at presentation Stable or progressive disease during neoadjuvant chemotherapy
Correct answer is D. RATIONALE: Surgery should not be performed in the presence of inflammatory signs. Thus, radiation may be needed if there is either an incomplete response, stable disease, or disease progression to induction chemotherapy. Matted axillary nodes or dermal lymphatic invasion at presentation are not contraindications to surgery after a good response to chemotherapy. Skin-sparing mastectomy or breast conservation should not be used in patients with inflammatory breast cancer. 289.
Which of the following management options would be most appropriate for low-grade chondrosarcoma? A. B. C. D.
Curettage for primary treatment of affected extremity sites Curettage and cryotherapy for primary treatment of affected axial and pelvic sites Postoperative neutron radiation therapy after complete surgical resection Postoperative photon radiation therapy of >65 Gy
Correct answer is D. RATIONALE: Options A and B (see references 1 and 4 below): Tumors treated with curettage and cryotherapy have lower or comparable recurrence rates (6%) to enblock resection (25%) at extremity sites. En-block resection recurrences (17%) are lower for axial-pelvic sites when compared to curettage and cryotherapy (43%). Option C (see reference 2 below): Neutrons have been used for treatment of unresectable sarcomas. Option D (see reference 3 below): Optimal treatment of chondrosarcoma requires doses of >65 Gy. REFERENCES: (1) Chow, W.A. Update on chondrosarcomas. Current Opinion in Oncology. 2007;19:371376. (2) Gunderson & Tepper eds. Clinical Radiation Oncology. 2nd edition, 2007;379. (3) Gunderson & Tepper eds. Clinical Radiation Oncology. 2nd edition, 2007;549- 552. (4) Gelderblom H, Hogendoorn PCW, Dijkstra SD, et al. The clinical approach towards chondrosarcoma. The Oncologist. 2008;13:320-329.
290.
Which of the following statements about thyroid malignancies is true? A. Papillary carcinoma spreads most commonly to level 2 lymph nodes. B. Older patients with papillary carcinoma have a better prognosis than younger patients. C. Tumor size is the most important prognostic factor for a resectable follicular cancer. D. Hürthle cell carcinoma has a worse prognosis than other well-differentiated malignancies.
Correct answer is D. RATIONALE: The rationale for this question is to demonstrate the importance of age and certain pathologies in the prognosis of patients with thyroid malignancies. Hürthle cell cancer has a decreased avidity for 131I; therefore, treatment with radioactive iodide has a limited efficacy. Hürthle cell cancer reportedly behaves in a more aggressive fashion than other well-differentiated thyroid cancers, with a tendency to have a higher incidence of metastasis and a lower survival rate. This is truer for the lesions that are clearly demonstrated to be malignant and in patients who are considered to be at high risk based on such factors as age, tumor size, invasiveness, and the presence of metastasis. Widely invasive tumors behave more aggressively. Recurrence among patients with Hürthle cell carcinoma is considered to be incurable. 291.
A 32-year-old woman has clinical stage IIA Hodgkin lymphoma. Which of the following doses of radiation therapy would be most appropriate if the patient achieves a complete response after 6 cycles of ABVD chemotherapy? A. B. C. D.
44 Gy 36 Gy 30.6 Gy 20 Gy
Correct answer is C. RATIONALE: National Comprehensive Cancer Network guidelines specify a radiation dose of 30 Gy for treatment of non-bulky clinical stage IIA Hodgkin lymphoma. 292.
In treating a superficial bone lesion, a radiation oncologist prescribes 40 Gy in 2 Gy daily fractions. This prescription is an example of: A. B. C. D.
radiation exposure. kinetic energy released in a medium (KERMA). absorbed dose in a medium. absorbed dose in air.
Correct answer is C. RATIONALE: This item requires knowledge of the definition of absorbed dose in a medium (in this instance, bone is the medium).
293.
The figure below shows two cell survival curves, one exponential and one shouldered. To calculate the RBE, the dose corresponding to Point "X" should be compared to the dose corresponding to Point:
A. B. C. D.
I. II. III. IV.
Correct answer is C. RATIONALE: RBE is defined as the ratio of doses of a standard versus “test” type of radiation to yield the same biological endpoint (i.e., an isosurvival of cells in this example). Accordingly: RBE = Dose corresponding to Point III / Dose corresponding to Point X. 294.
Which of the following conditions is a contraindication for performing a radical resection on a patient with adenocarcinoma of the pancreas? A. B. C. D.
Tumor invasion of the splenic artery Tumor encasement of the superior mesenteric artery Involvement of the peripancreatic lymph nodes Extensive pancreatic intraepithelial neoplasia
Correct answer is B. RATIONALE: Encasement of the superior mesenteric artery (SMA) is a contraindication of a Whipple procedure and is of major importance in pretreatment planning (i.e., definitive chemoradiation versus surgery). 295.
Which of the following subtypes of ependymoma has the lowest risk of recurrence after gross total resection alone? A. B. C. D.
Thoracic spine, low grade Supratentorial, anaplastic Fourth ventricular, tanycytic Filum terminale, myxopapillary
Correct answer is D. RATIONALE: The myxopapillary subtype of ependymoma is generally more indolent as often occurs in the lumbosacral region. Tumors of the filum terminale usually can be more completely resected and have a better prognosis than tumors of other sites.
296.
Which of the following radionuclides has the longest half-life, based on its decay constant (λ)? A. B. C. D.
103
Pd (λ= 0.041/day) I (λ= 0.0117/day) 131 Cs (λ= 0.0714/day) 198 Au (λ= 0.257/day) 125
Correct answer is B. RATIONALE: This item requires knowledge that T1/2 is inversely proportional to the decay constant (λ), or that the half-life T1/2 = 0.693/λ. Hence, radionuclide 125 I, which has the smallest transformation (decay) per day, exhibits the longest half-life. 297.
Low-grade oligodendrogliomas most commonly are located in the: A. B. C. D.
cerebellum. parietal lobe. frontal lobe. hippocampus.
Correct answer is C. RATIONALE: Low-grade oligodendrogliomas most commonly occur in the frontal lobe. 298.
Which of the following statements best explains the conventional dose rate effect? A. B. C. D.
As the dose rate decreases, PLD repair is stimulated. As the dose rate increases, PLD repair is inhibited. As the dose rate decreases, SLD repair occurs during irradiation. As the dose rate increases, SLD repair is inhibited.
Correct answer is C. RATIONALE: The explanation for the conventional dose rate effect, the observation of decreasing biological effectiveness (both in vitro and in vivo) of irradiation as the dose rate is lowered, is that sublethal damage (SLD) repair occurs during radiation exposure (which is longer the lower the dose rate for a given total dose). Further, it should be noted that DNA repair enzymes are, in most cases, constitutively present and active in normal cells and need only be “mobilized” in response to DNA damage. Thus, stating that a particular damaging agent like ionizing radiation “stimulates” or “inhibits” repair is a bit simplistic and misleading. REFERENCE: Hall and Giaccia. Radiobiology for the Radiologist. 6th edition. Chapter 5. 299.
The addition of early thoracic radiation therapy to chemotherapy for patients with limited-stage SCLC is expected to improve overall survival at 3 years by: A. B. C. D.
00%. 05%. 10%. 15%.
Correct answer is B. RATIONALE: In the meta-analysis of the thoracic radiation therapy trials, the overall survival rate was improved by 5.4% at 3 years in patients who received radiation therapy in addition to chemotherapy for limited-stage SCLC.
300.
Which of the following pathological features is characteristic of nodular lymphocyte-predominant Hodgkin lymphoma? A. B. C. D.
CD15−, CD30+, CD20+ CD15+, CD20+, CD22+ CD15+, CD30+, CD20− CD20+, CD15−, CD30−
Correct answer is D. RATIONALE: Nodular lymphocyte-predominant Hodgkin lymphoma has distinct pathological features characterized by the presence of CD20+, CD15-, and CD30- cells. These features are different from classic Hodgkin lymphoma, which does not express CD20. 301.
Which of the following diagnostic imaging time points for tumor assessment should be used for EBRT target volume definition in a 3-year-old child with stage 4, high-risk neuroblastoma? A. B. C. D.
Preinduction chemotherapy Postinduction chemotherapy but preoperative Postoperative Post-PBSCT
Correct answer is B. RATIONALE: The postinduction, preoperative tumor volume allows coverage of the sites of risk and sparing of normal tissues if anatomy was distorted by mass effect of the tumor. 302.
Which of the following types of ionization chamber is best for measuring surface dose? A. B. C. D.
Farmer Parallel plate Well chamber Transmission chamber
Correct answer is B. RATIONALE: Parallel-plate ionization chambers (or extrapolation chambers) are the most suitable chambers for surface dosimetry because of their geometry and ability to measure dose in thin volumes close to the surface. 303.
Which of the following histologies is most commonly associated with small bowel cancer? A. B. C. D.
Carcinoid Sarcoma Lymphoma Adenocarcinoma
Correct answer is D. RATIONALE: Adenocarcinoma — 45%; carcinoid — 29%; lymphoma — 16%; sarcoma — 10%. REFERENCE: Journal of National Cancer Institute. April 1987;78(4):653-6.
304.
Patients with breast cancer are routinely tested for the activity of which of the following oncogenes? A. B. C. D.
ABL ERB MYC RAS
Correct answer is B. RATIONALE: Screening for the activity of Her-2, a member of the ERB oncogene family, is routinely carried out in patients with newly diagnosed breast cancer. Treatment with the molecularly targeted drug Herceptin is indicated only in patients who test positive for overexpression of Her-2. 305.
Randomized trials involving dose escalation of EBRT for prostate cancer have consistently shown a significant difference in which of the following endpoints? A. B. C. D.
Distant-metastases-free survival PSA-failure-free survival Grade 2-3 rectal toxicity Grade 2-3 urinary toxicity
Correct answer is B. RATIONALE: The randomized dose-escalation trials primarily have seen a benefit in PSA control rates and not a benefit in the other endpoints. 306.
Which of the following outcomes is associated with cisplatin-based adjuvant chemotherapy for NSCLC? A. B. C. D.
Reduction in the risk of death by about 10% Improved 5-year disease-free survival by about 10% Absolute benefit of 10% in 5-year disease-free survival Absolute benefit of 10% in 5-year overall survival
Correct answer is A. RATIONALE: According to the Lung Adjuvant Cisplatin Evaluation (LACE) and meta-analysis, cisplatin-based adjuvant chemotherapy improves survival among patients who have completely resected NSCLC with approximately 10% reduction in the risk of death, with absolute benefits in 5-year disease-free and overall survival rates of 5%. REFERENCES: Journal of Clinical Oncology (JCO). 2008;(26)3552-9. New England Journal of Medicine (NEJM). 2004;350(4):315-60. 307.
Which of the following statements about cholangiocarcinomas is true? A. B. C. D.
Surgery provides curative results in the majority of patients. The majority of patients present with metastatic disease. Proximal lesions have a worse prognosis than distal lesions. Regional lymph nodes are rarely involved.
Correct answer is C. RATIONALE: Surgery, although having poor outcomes, is the mainstay of treatment for cholangiocarcinoma. Distal lesions have better outcomes than proximal tumors.
308.
Which of the following statements about the overview analysis by the Early Breast Cancer Clinical Trialists' Cooperative Group (EBCTCG) on the benefit of adjuvant irradiation for patients with breast cancer is true? A. The 5-year locoregional recurrence rate is 42% for patients undergoing breastconserving surgery (BCS) alone. B. For every four locoregional recurrences avoided at 5 years, one breast-cancerrelated death is avoided at 15 years. C. The 15-year gain in the breast cancer mortality rate is 18% for patients undergoing BCS and radiation therapy versus BCS alone. D. When the 5-year locoregional recurrence rate is reduced by >10%, an improvement in the mortality rate will emerge at 10 years.
Correct answer is B. RATIONALE: Option A: The 5-year locoregional recurrence rate for breast-conserving therapy (BCT) alone was 32%. Option C: The 15-year gain in breast cancer mortality for BCS + radiation therapy (RT) vs BCS alone was 5.4%. Option D: When there is a greater than 10% reduction in the 5-year locoregional recurrence, the mortality benefit will emerge at 5 years. REFERENCES: Lancet. 2005;365:1687-1717. Overview analysis, Early Breast Cancer Clinical Trialists' Cooperative Group (EBCTCG). 2005. 309.
Which of the following statements about a static wedge used with a 6-MV linear accelerator is FALSE? A. B. C. D.
The wedge causes a spectral change in the beam. The wedge transmission factor varies with the field size. The wedge transmission factor varies with the depth. The percent depth dose is the same with or without the wedge.
Correct answer is D. RATIONALE: The percent depth dose will change since there is beam hardening for 6-MV photons due to the metal wedge. 310.
Which of the following organs is most likely to experience dysfunction after whole-organ irradiation? A. B. C. D.
Liver Brain Lung Esophagus
Correct answer is C. RATIONALE: For total organ irradiation using conventionally sized daily dose fractions, the total dose to cause an approximately 5% probability of severe, irreversible lung damage within 5 years of treatment is approximately 18 Gy, far lower than the dose for the other organs listed. In fact, the lung is among the most sensitive of the late-responding normal tissues, with the critical factors determining tolerance being the total dose delivered, the fraction size, and the volume irradiated. REFERENCES: Hall and Giaccia. Radiobiology for the Radiologist. 6th edition, Chapter 19 (Table 19.2). Mettler and Upton. Medical Effects of Ionizing Radiation. 3rd edition, Chapter 1 (Table 1-8) and Chapter 6.
311.
What is the 5-year pelvic failure rate (ie, vagina, paravagina, inguinal and iliac lymph nodes) of stage I carcinoma of the vagina treated with radiation therapy to 80 Gy alone? A. B. C. D.
<5% 15% 25% 35%
Correct answer is B. RATIONALE: The largest series (MDACC) of 193 patients reports a 10% vaginal failure rate and a 15% pelvic local failure rate. This is consistent with Mallinkrodt and Stanford. REFERENCES: Frank, et al. International Journal of Radiation Oncology, Biology, and Physics (IJROBP). 2005;62:1. Perez. International Journal of Radiation Oncology, Biology, and Physics (IJROBP). November/December 2005;15(6):1283-90. Tran, et al. Gynecological Oncology. June 2007;105(3):641. 312.
Which of the following tumor markers is commonly elevated in patients with hepatocellular carcinoma, but is rarely elevated in patients with cholangiocarcinoma? A. B. C. D.
CEA CA 19-9 AFP β-hCG
Correct answer is C. RATIONALE: α-Fetoprotein (AFP) is rarely positive in cholangiocarcinoma but is found in 35% to 75% of hepatomas. This may help distinguish between the two conditions during the initial workup. 313.
Which of the following treatments achieves the best disease control in patients with primary CNS lymphoma? A. B. C. D.
Corticosteroids Whole-brain radiation therapy Debulking of the tumor mass before administration of chemoradiation Postsurgical chemotherapy only
Correct answer is B. RATIONALE: It is important to avoid use of corticosteroids prior to establishing a histological diagnosis since they can cause a change in tumor appearance. Surgical resection will not affect disease outcome because of its multifocal nature. For the same reason, whole-brain irradiation is warranted for achieving disease control. Compared to all the modalities, radiation therapy is associated with the worse neurotoxicity, particularly in elderly patients. 314.
Which of the following types of tumor is most likely associated with the EGFR V3 mutant? A. B. C. D.
Glioblastoma Meningioma Squamous cell carcinoma Nasopharyngeal carcinoma
Correct answer is A. RATIONALE: The V3 mutant of EGFR is associated with glioblastoma (GBM). The presence of this mutation suggests that not all EGFR-based therapies will be active in GBM. EGFR V3 specific immunotherapies are in phase III clinical trials.
315.
Which of the following statements about IMRT is true? A. B. C. D.
Dynamic IMRT is more conformal than step-and-shoot IMRT. Image guidance is required to perform IMRT. IMRT requires inverse treatment planning. The first form of IMRT was helical tomotherapy.
Correct answer is C. RATIONALE: Because of the large numbers of treatment beamlets that need to be optimized, a computerized inverse treatment planning is required for IMRT. 316.
For radiation-induced normal tissue toxicity, the term TD50/5 refers to the: A. total radiation dose for which there is a 50% probability of developing toxicity within 5 years of irradiation. B. total radiation dose for which there is a 5% probability of developing toxicity within 5 years of irradiation. C. probability of developing toxicity 5 years after 50 Gy of irradiation. D. probability of developing toxicity 5 months after 50 Gy of irradiation.
Correct answer is A. RATIONALE: The definition of the term "TD50/5" (or "50% Tolerance Dose at 5 Years") is the total radiation dose that would yield an approximately 50% probability of causing an unacceptable normal tissue complication within 5 years of the completion of radiotherapy. REFERENCE: Mettler and Upton. Medical Effects of Ionizing Radiation. 3rd edition, Chapter 1 (Table 1-8). 317.
Which of the following paraneoplastic syndromes are associated with SCLC? A. B. C. D.
SIADH, hypercalcemia, and Cushing syndrome SIADH, limbic encephalitis, and Lambert-Eaton syndrome Lambert-Eaton syndrome and hypercalcemia Cushing syndrome and thrombocytosis
Correct answer is B. RATIONALE: Hypercalcemia is classically encountered in squamous cell carcinoma, but not in SCLC. Thrombocytosis has not been described, although thrombocytopenia may occur. 318.
Compared with CT images, MR imaging has which of the following disadvantages for the purpose of treatment planning? A. B. C. D.
Reduced soft tissue contrast Inability to acquire functional information Limited usefulness for treatment sites other than the brain Susceptibility to spatial distortions
Correct answer is D. Of all the answers provided, option D is the only one that is correct. Compared to CT, MR imaging provides improved soft tissue contrast, the ability to acquire functional imaging information, and has proven to be quite useful in treatment sites beyond the brain.
319.
Which of the following phenotypic characteristics would be increased in cells that are defective in the FEN1 endonuclease, which is known to be involved in base excision repair (BER)? A. B. C. D.
Mutation rate Sensitivity to UV irradiation Sensitivity to alkylating agents Sensitivity to ionizing radiation
Correct answer: ABCD. RATIONALE: UV, alkylating agents, and ionizing radiation generally do not produce the types of DNA damage repaired by base excision repair, such that a defect in the FEN1 endonuclease should not produce a particular sensitivity-associated phenotype. A BER defect will lead to an overall increase in genomic instability and mutation rate, however. REFERENCE: Henneke G, Friedrich-Heineken E, and Hubscher U. Flap endonuclease 1: A novel tumor suppresser protein. Trends in Biochemical Sciences. 2003;28:384-390. 320.
Which of the following factors has been found to affect the outcome of salvage therapy in patients with relapsed Hodgkin lymphoma? A. B. C. D.
Performance status Extranodal site of relapse Lactate dehydrogenase (LDH) levels Erythrocyte sedimentation rate (ESR)
Correct answer is A. RATIONALE: The following factors are found to affect the outcome of patients with relapsed disease: duration of remission after initial therapy for <1 year, presence or absence of "B" symptoms, Karnofsky performance status <90, age >40 years. 321.
Which of the following viruses has been identified as a causative agent in the development of cervical cancer? A. B. C. D.
Epstein-Barr virus Human papillomavirus Human T-lymphotropic virus Hepatitis C virus
Correct answer is B. RATIONALE: Several viruses have been identified as causative agents in different human tumors. The role of human papilloma viruses (HPV), particularly subtypes 16 and 18, has been established in cervical cancer and a HPV recombinant vaccine for the prevention of cervical cancer has been approved by the U.S. Food and Drug Administration. Epstein Barr Virus (EBV), Hepatitis C Virus (HCV) and the Human T-Lymphotropic Virus (HTLV) have been linked with Burkitt's lymphoma, hepatocellular carcinoma, and T-cell leukemia, respectively.
322.
When matching a tangential breast field to a supraclavicular field, the collimator for the tangential field must be rotated. The rotation of the collimator is a function of which of the following two treatment parameters? A. B. C. D.
SSD and field size SSD and gantry angle Field size and gantry angle Isocenter depth and gantry angle
Correct answer: ABCD. RATIONALE: To avoid an overlap between the supraclavicular and tangential fields, collimator rotation must be utilized to match the inferior edge of the supraclavicular field with the superior edge of the tangential fields. Since the beam edges are matched on the patient’s skin surface, the collimator rotation will be independent of the isocenter depth, and SSD and will be dependent on the field size and the gantry angles used for the treatment fields. 323.
In response to radiation-induced DNA damage, p53 increases the expression of which of the following gene products? A. B. C. D.
Cyclin A Cyclin E 53BP1 p21
Correct answer is D. RATIONALE: p53 is the protein product of the crucially important tumor suppressor gene TP53 and functions as a transcriptional activator. DNA damage-induced G1 arrest is governed by p53-mediated transactivation of p21, which inhibits G1 cyclins and therefore prevents movement of cells from G1 into S phase. REFERENCE: Tannock, Hill, Bristow, and Harrington. The Basic Science of Oncology. 4th edition, Chapter 7. 324.
A 54-year-old man who underwent TURBT and intravesicular BCG for superficial bladder cancer 3 years ago now presents with painless hematuria. A repeat cystoscopy is normal. What is the next most appropriate test? A. B. C. D.
Ultrasound of the bladder Ultrasound of the prostate Intravenous pyelogram Serum PSA level
Correct answer is C. RATIONALE: Patients with a history of prior superficial bladder cancers may be at increased risk for other tumors of the upper tracts. Given the choices, intravenous pyelogram (IVP) is the most appropriate next step given a negative cystoscopy. 325.
Given the same field size at the prescription depth, which of the following factors is different for an isocentric setup and an SSD setup with SSD = 120 cm? A. B. C. D.
Linac calibration factor Tissue-maximum ratio (TMR) Phantom scatter factor (Sp) Collimator scatter factor (Sc)
Correct answer is C. RATIONALE: The effective field size increase at the surface will affect the scatter linearly. The other factors are independent.
326.
Which of the following risk factors has NOT been shown to be associated with the development of anal cancer? A. B. C. D.
HIV infection HPV infection HSV infection Multiple sexual partners
Correct answer is C. REFERENCE: Ryan DP, Compton CC, Mayer RJ. Carcinoma of the anal canal. New England Journal of Medicine (NEJM). March 16, 2000;342(11):792-800. 327. When inactivated, which of the following genes abolishes both the cytotoxic and radiosensitizing effects of gemcitabine? A. B. C. D.
ATM MLH1 BCL-2 TP53
Correct answer is B. RATIONALE: Gemcitabine is a pyrimidine analog that functions as an antitumor agent and potent radiosensitizer through depletion of the deoxynucleoside triphosphate pool and subsequent incorporation into DNA, resulting in inhibition of DNA synthesis and repair. A functional mismatch repair (MMR) system is critical for gemcitabine to be active. Defects in MMR, in particular the loss of MLH1, abolishes both the cytotoxicity and radiosensitizing effect of gemcitabine.REFERENCE: 328.
According to the GOG 99 (Keys) adjuvant endometrial trial, what percent of patients undergoing pelvic irradiation had grade 3 and 4 gastrointestinal toxicities? A. B. C. D.
00% 04% 08% 16%
Correct answer is C. RATIONALE: This question demonstrates that pelvic radiation can have a high morbidity rate (8% with severe GI toxicities) if not administered judiciously. REFERENCE: Keys, et al. Gynecological Oncology. March 2004;92(3):744-51. 329.
Which of the following findings is most common at diagnosis of patients with renal cell cancer? A. B. C. D.
Approximately 75% of patients have metastases to the lung. Approximately 40% of patients have lymph node involvement. The bone is the most common site of metastasis. The renal vein is invaded in 5% of cases.
Correct answer: ABCD. RATIONALE: Approximately 75% of patients with metastatic renal cell cancer (RCC) have metastases to the lung, 36% to the soft tissues, 20% to the bone, 18% to the liver, 8% to the cutaneous sites, and 8% to the central nervous system. Lymph node metastases occur with an incidence of 9% to 27% and most often involve the renal hilar, paraaortic, and paracaval lymph nodes. The renal vein is invaded in 21% of cases.
330.
Which of the following conditions most commonly is found in patients with Langerhans cell histiocytosis? A. B. C. D.
Diabetes insipidus Hyperthyroidism SIADH secretion Precocious puberty
Correct answer is A. RATIONALE: Diabetes insipidus is seen in patients with Langerhans cell histiocytosis (LCH) because of histiocytic infiltration of the hypothalamus and pituitary gland. 331.
The Bcl-2 gene is a: A. B. C. D.
tumor suppressor. tyrosine kinase inhibitor. proto-oncogene. initiator.
Correct answer is C. RATIONALE: Bcl-2 is a proto-oncogene that is responsible for transcriptional deregulation. It negatively affects normal apoptosis in lymphoid malignancies, especially follicular lymphoma. REFERENCE: Devita. p. 2219. 332.
Which of the following prognostic factors is most important in determining the risk for distant metastases and the overall survival rate for adults with soft tissue sarcoma? A. B. C. D.
Tumor size Tumor grade Histologic subtype Performance status
Correct answer is B. RATIONALE: Tumor grade has the most important influence on outcome. 333.
Which of the following functions is NOT served by cell cycle checkpoints? A. B. C. D.
Preventing cells from progressing through the cell cycle with residual DNA damage Identifying cells with irreparable DNA damage and targeting them for elimination Increasing DNA repair rates Helping maintain genomic stability
Correct answer is C. RATIONALE: Cell cycle checkpoints induced by DNA-damaging agents, such as ionizing radiation, temporarily halt cell cycle progression to allow DNA repair processes to occur. The function of cell cycle checkpoints is to prevent genetic instability and increase cell survival by preventing cell propagation in the presence of residual DNA damage. Proteins involved in cell cycle checkpoint control are attractive targets for the development of novel anticancer drugs.
334.
Which of the following ionization chambers is used as the primary standard in the measurement of Roentgens (R)? A. B. C. D.
Free-air Thimble Parallel plate Extrapolation
Correct answer is A. RATIONALE: While all of the above are ionization chambers, the free-air chamber is a very large chamber in comparison. According to the definition of roentgen, the ionized electrons produced by photon interactions in the gas medium of the chamber volume must be collected within the chamber volume. For small-volume chambers (options B-C), this is not feasible. 335.
What is the risk of recurrence in the paraaortic or pelvic lymph nodes after orchiectomy alone for stage I pure seminoma? A. B. C. D.
<5% 20% 35% 50%
Correct answer is B. RATIONALE: From multiple surveillance studies, the risk of recurrence for patients with stage I seminoma is between 15% to 20%. REFERENCE: Princess Margaret, Royal Marsden study. 336.
What is the most common histology in women with urethral carcinoma? A. B. C. D.
Transitional cell carcinoma Squamous cell carcinoma Adenosquamous carcinoma Adenocarcinoma
Correct answer is B. RATIONALE: The most common tumor in women with urethral carcinoma is squamous cell carcinoma, comprising more than 50% of patients. The next most common histologies in order of frequency are transitional cell and adenocarcinoma. 337.
IMRT does NOT decrease the incidence of which of the following complications of nasopharyngeal cancer? A. B. C. D.
Dysphagia Xerostomia Hearing loss Osteoradionecrosis
Correct answer is D. RATIONALE: Dose constraints have been established for salivary gland, cochlea, and constrictor muscles.
338.
Which of the following statements about genetic breast cancer predispositions is true? A. Patients with a BRCA2 germline mutation have a higher risk of colon cancer than patients with a BRCA1 germline mutation. B. BRCA1 and BRCA2 germline mutations have an autosomal-dominant inheritance pattern. C. Peutz-Jegher syndrome is associated with a strong family history of follicular thyroid cancer. D. Brain and soft tissue malignancies are associated with a BRCA1 germline mutation.
Correct answer is B. RATIONALE: BRCA1 is associated with breast and ovarian cancers. BRCA2 is associated with breast, ovarian, prostate, and pancreatic cancers. Li Fraumeni syndrome is associated with breast, brain, soft tissue sarcoma, osteosarcoma, leukemia, and adrenocortical carcinomas. Cowden's disease is associated with breast, ovarian, follicular thyroid, and colon cancers. Peutz-Jegher syndrome is associated with GI and breast cancers. REFERENCE: Harris, Lippman, Morrow, and Osborne. Diseases of the Breast. 3rd edition. 2004;279. 339.
In a radiation survival curve experiment using a human tumor cell line, 300 cells were seeded into Petri dishes and cultured for 14 days before being stained. There were 150 resulting colonies. In a second set of Petri dishes, 1,000 cells were seeded and irradiated with 4-Gy x-rays. Fourteen days later, there were 180 resulting colonies. What was the surviving fraction after 4-Gy x-ray irradiation? A. B. C. D.
0.090 0.036 0.18 0.36
Correct answer is D. RATIONALE: The normalized cell surviving fraction in a radiation survival curve experiment is calculated from the absolute surviving fraction after a given dose of radiation, divided by the plating efficiency (i.e., the absolute surviving fraction obtained from a cohort of cells prepared during the same experiment and under the same experimental conditions, but not exposed to radiation). Therefore, for a dose of 4 Gy in this case: SF = (180/1,000) ÷ (150/300) = 0.18/0.50 = 0.36. 340.
Which of the following histologies is most commonly associated with primary vaginal cancer in women who are younger than 20 years of age? A. B. C. D.
Sarcoma Melanoma Squamous cell carcinoma Adenocarcinoma
Correct answer is D. RATIONALE: Adenocarcinoma is the second most common histology (after squamous cell) and represents nearly all patients (86%) younger than 20 years of age. Sarcoma, particularly pediatric sarcomas, was a smaller group. This study covers the years of 1985-1994. REFERENCE: Creasman WT, et al. National cancer data basic report on cancer of the vagina. Cancer. September 1, 1998; 83(5):1033-40.
341.
Which of the following IMRT features is theoretically associated with an increased risk for secondary malignancies? A. B. C. D.
It increases the whole-body dose. It does not provide effective sparing of critical organs. It is performed with smaller PTV margins. It uses fewer monitor units than conventional radiation therapy.
Correct answer is A. RATIONALE: Because of the increased treatment times and significant leakage through the MLC leaves, the dose to normal tissue is significantly increased with IMRT compared to non-IMRT therapy. As a result, this has raised concerns about the potential for increased incidence of secondary malignancies. 342.
Which of the following radiation doses to metastatic sites is recommended after PBSCT in a 3-year-old child who has high-risk neuroblastoma with multiple bony metastases on 131 I-metaiodobenzylguanidine (MIBG) scan at diagnosis? A. B. C. D.
21.6 Gy to all initial sites 45 Gy to all initial sites 21.6 Gy to persistent sites on MIBG scan after induction chemotherapy 45 Gy to persistent sites on MIBG scan after induction chemotherapy
Correct answer is C. RATIONALE: Current treatment regimens recommend 20-25 Gy to metastatic sites, which are resistant to the initial chemotherapy. 343.
Which of the following outcomes was demonstrated in the ECOG E1482 (Horning) trial, which randomized involved-field radiation therapy (IFRT) versus observation after 8 cycles of CHOP in patients with high- and intermediate-risk stage I or stage II non-Hodgkin lymphoma? A. Time to progression was the same in both study groups. B. Overall survival improved in patients who received IFRT after having a complete response to chemotherapy. C. Six-year disease-free survival and failure-free survival improved in patients who received IFRT after having a complete response to chemotherapy. D. Failure-free survival improved in patients who received IFRT after having a partial response to chemotherapy.
Correct answer is C. RATIONALE: Patients with a complete response had improved 6-year disease-free survival (DFS), failure-free survival (FFS), and time to progression in the IFRT arm over the observation arm, but there was no difference in overall survival (OS). Patients achieving a complete response (CR) after 8 cycles of CHOP were treated to 30 Gy of IFRT, while patients with a partial response received 40 Gy of IFRT. Conversion to CR did not significantly influence clinical outcome of patients with initial PR from chemotherapy. REFERENCE: Horning, et al. Journal of Clinical Oncology (JCO). 2004;22(15).
344.
According to the GITSG 9173 trial, which of the following outcomes was associated with patients who had resected pancreatic cancer? A. The median overall survival improved from 11 months to 20 months for patients in the chemoradiation arm. B. The number of distant metastasis was decreased for patients in the chemoradiation arm versus the observation arm after surgery. C. The same rate of survival was found in patients with positive margins as in those with negative margins. D. A radiation dose of 60 Gy was superior to 40 Gy.
Correct answer is A. RATIONALE: This trial established the precedent of treating resected pancreatic cancer with chemoradiation. 345.
What is the 5-year local recurrence rate for a completely resected grade I meningioma? A. B. C. D.
01% 10% 20% 30%
Correct answer is B. RATIONALE: The recurrence rate for a completely resected grade I meningioma at 5 years is 10% (1% to 2% per year). 346.
Which of the following assays has been used to measure the radiation sensitivity of bone marrow stem cells in vivo? A. B. C. D.
Fat pad Lung colony Spleen colony Endpoint dilution
Correct answer is C. RATIONALE: Clonogenic assays measure cellular reproductive integrity, and all have as their endpoint the ability of single cells to form colonies containing at least 50 cells (corresponding to a minimum of approximately 5 successful rounds of cell division). Clonogenic assays can be conducted both in vitro and in vivo (providing a particular normal tissue is amenable to substituting for a Petri dish as a vessel allowing colony growth) in laboratory rodents. The fat pad, lung colony, and endpoint dilution assays are used to assess the radiosensitivity of tumor cells, whereas the spleen colony assay measures the radiation sensitivity of normal bone marrow stem cells. 347.
Which of the following mediums is most commonly used in the United States to report the absorbed dose for patients who are NOT on an RTOG protocol? A. B. C. D.
Water Tissue Bone Fat
Correct answer is A. RATIONALE: This item requires knowledge of the definition of absorbed dose to a medium. Water is the medium of choice, but absorbed doses for patients on an RTOG protocol are reported as absorbed dose to tissue.
348.
Which of the following tests describes a regression method used when the outcome is censored and the regression coefficients are interpreted as adjusted relative risk or odds ratios? A. B. C. D.
Log-linear ANCOVA Mantel-Haenszel Cox proportional hazards model
Correct answer is D. RATIONALE: Cox proportional hazards model is a regression method used when the outcome is censored. The regression coefficients are interpreted as adjusted relative risk or odds ratio. Log-linear analyzes the relationships among three or more nominal variables (not censored) and may be used as a regression method to predict a nominal outcome from nominal independent variables. ANCOVA (analysis of covariance) is a special type of analysis of variance or regression used to control for effect of a possible confounding factor. Mantel-Haenszel test is a statistical test of two or more 2 x 2 tables used to compare survival distributions or to control for confounding factors. 349.
Which of the following histologic findings is most characteristic of Ewing's sarcoma tumor cells? A. B. C. D.
Vimentin staining is usually positive. Cytokeratin staining is usually positive. Cells are large with small hypochromatic nuclei. Cells are in Homer-Wright rosette pattern.
Correct answer is A. RATIONALE: The tumor cells are small with hyperchromatic nuclei, typically in a pseudorosette pattern. The cells undergo frequent mitosis. Vimentin staining is uniformly positive, and cytokeratin staining is usually negative. 350.
Based on a meta-analysis of randomized breast cancer prospective trials published in 2005 (Mauri), which of the following outcomes is associated with neoadjuvant chemotherapy compared to adjuvant chemotherapy for patients who received breast-conserving therapy? A. B. C. D.
The locoregional recurrence rate is increased. The distant recurrence rate is reduced, but the overall survival is improved. There is a lower incidence of involved margins after breast-conserving surgery. Tumors that have a complete clinical response to neoadjuvant chemotherapy and preoperative irradiation do not require surgical resection.
Correct answer: ABCD. RATIONALE: The meta-analysis showed an increased locoregional recurrence rate with neoadjuvant chemotherapy, particularly when radiation was given without surgery. There was no data on margins presented. There was no difference in distant recurrence or survival. REFERENCE: Mauri, et al. Journal of National Cancer Institute. 2005;97:188-94.
351.
Bremsstrahlung radiation is defined as a process in which an electron: A. passing near a nucleus is accelerated and deviates from its straight-line path (ie, called "braking" radiation). B. passing near a nucleus is accelerated but maintains its straight-line path (ie, called "speeding" radiation). C. passing near a nucleus is annihilated and produces an electron-positron pair (ie, called "annihilation" radiation). D. directly strikes a nucleus, and the electron is annihilated (ie, called "collision" radiation).
Correct answer is A. RATIONALE: It requires an understanding of the definition of bremsstrahlung radiation. 352.
Which of the following serum levels is LEAST likely to be elevated in a patient with pure seminoma? A. B. C. D.
Lactate dehydrogenase β-human chorionic gonadotropin α-Fetoprotein Calcium
Correct answer is C. RATIONALE: In pure seminoma, α-fetoprotein (AFP) serum levels should not be elevated. 353.
What is the primary reason that an 8 Gy x-ray dose delivered at 1 Gy/h is less toxic than the same dose delivered at 1 Gy/min? A. B. C. D.
Fewer free radicals are generated. Free-radical scavenging occurs. SLD repair occurs during irradiation. Cell division occurs during irradiation.
Correct answer is C. RATIONALE: A given total dose delivered at a high dose rate is more toxic than the same dose delivered at a low dose rate because of the conventional dose rate effect. This results because sublethal damage repair occurs during the radiation exposure, which, for a given total dose, takes longer the lower the dose rate. 354.
According to the prospective Phase III (Landoni) trial for stage IB-IIA cervical cancer, the severe treatment morbidity rate with definitive radiation therapy versus radical surgery was: A. B. C. D.
lower. comparable. higher. not analyzed.
Correct answer is A. RATIONALE: Patients receiving irradiation had a statistically significant lower rate of severe sequelae (12 vs 28%, P < 0.0004) than women randomized to receive radical surgery. The markedly higher rate of severe toxicity in the surgical group may be due, in part, to the addition of adjuvant pelvic irradiation during surgery for patients with adverse prognostic features. REFERENCE: Landoni, et al. Lancet. 1997;350:535-540 (which randomized 343 patients with clinical stage IB-IIA cervical cancer to receive definitive irradiation versus radical surgery).
355.
During inverse treatment planning, an end-of-planning correction accounts for: A. B. C. D.
dynamic arc delivery. patient setup and intra-fraction motion. leaf motion and transmission. dose calculation uncertainties.
Correct answer is C. RATIONALE: During inverse treatment planning, beamlets used in optimization are typically considered "ideal." Practical delivery aspects, particularly leaf motion and transmission, are accounted at the end of optimization for the plan. The residual errors are typically small. 356.
According to the German Rectal Cancer Study Group (Sauer) trial, patients who received preoperative chemoradiation experienced which of the following outcomes in comparison to those treated with postoperative chemoradiation? A. B. C. D.
Increased disease-free survival Increased acute toxicity Decreased local recurrence Decreased overall survival
Correct answer is C. RATIONALE: In the German trial, patients treated with preoperative chemoradiation had lower rates of locoregional recurrence and acute toxicity, with no difference in disease-free survival rates, compared to those treated with postoperative chemoradiation. REFERENCE: Sauer, et al. New England Journal of Medicine (NEJM), 2004;351:1731-40. 357. What is the most likely site of origin for an "unknown primary" head and neck tumor associated with the human papillomavirus? A. B. C. D.
Oral cavity Oropharynx Nasopharynx Hypopharynx
Correct answer is B. RATIONALE: There is emerging data suggesting that unknown primaries associated with the human papillomavirus (HPV) nearly always arise in the oropharynx. 358.
Rituximab binds to which of the following CD receptors? A. B. C. D.
CD20 CD15 CD8 CD4
Correct answer is A. RATIONALE: Rituximab is a chimeric monoclonal antibody that binds to the CD20 receptor expressed on B-cells to induce apoptosis. REFERENCE: FDA package insert.
359.
Which of the following subtypes of rhabdomyosarcoma has the worst prognosis? A. B. C. D.
Botryoid Alveolar Embryonal Spindle cell
Correct answer is B. RATIONALE: Alveolar rhabdomyosarcoma subtype, being younger than 1 year of age or older than 10 years of age, primary site, and higher stage or group are all independent prognostic factors for worse 5-year disease-free survival and overall survival outcomes. 360.
Why is patient positioning potentially more critical in the CT simulator than in the treatment rooms? A. B. C. D.
The CT simulator has a higher imaging resolution. Patient alignment errors in CT simulators translate into systematic treatment errors. CT simulators cannot provide volumetric and radiographic information. CT simulators are staffed at a lower level.
Correct answer is B. RATIONALE: If a patient is misaligned during CT simulation, this error can easily translate into a systematic treatment error (the patient can be consistently misaligned for treatment; therefore, option B is correct). The other answers provided are all false. Although a CT simulator may have a higher resolution than current electronic portal imagers, the imaging resolution of film is higher than that of a CT scan for institutions using verification film. In addition, a scan simulator can provide both a volumetric CT scan of the patient and two dimensional scout views, which are radiographic type images. Lastly, CT simulators are typically staffed at the same level as treatment units. Although there are instances when one therapist may be staffing the simulator, this is not typically the norm. Furthermore, although low staffing could potentially lead to errors such as positioning, such errors cannot always be associated with staffing levels.
