ABIM Medical Oncology — Questions and Answers
Question 1: Which electrolyte pattern is characteristic of tumor lysis syndrome?
- Hypokalemia, hypophosphatemia, hypercalcemia
- Hyperkalemia, hypophosphatemia, hypercalcemia
- Hypokalemia, hyperphosphatemia, hyperuricemia only
- Hyperkalemia, hyperphosphatemia, hypocalcemia, hyperuricemia (Correct answer)
Correct answer: Hyperkalemia, hyperphosphatemia, hypocalcemia, hyperuricemia
When tumor cells lyse they release potassium, phosphate, and nucleic acids, which are metabolized to uric acid. The excess phosphate binds calcium, which causes hypocalcemia.
Question 2: Per USPSTF (2021), at what age should average-risk adults begin colorectal cancer screening?
- 40
- 45 (Correct answer)
- 50
- 55
Correct answer: 45
In 2021 the USPSTF lowered the starting age for average-risk colorectal cancer screening from 50 to 45 because incidence is rising in younger adults.
Question 3: Which patient meets USPSTF (2021) criteria for annual low-dose CT lung cancer screening?
- A 62-year-old with a 25 pack-year history who quit 5 years ago (Correct answer)
- A 45-year-old current smoker with a 30 pack-year history
- A 70-year-old with a 10 pack-year history who smokes currently
- A 75-year-old with a 40 pack-year history who quit 20 years ago
Correct answer: A 62-year-old with a 25 pack-year history who quit 5 years ago
USPSTF recommends annual LDCT for adults aged 50–80 with at least a 20 pack-year history who currently smoke or quit within the past 15 years. Only the 62-year-old meets all three criteria.
Question 4: A patient with metastatic prostate cancer has new back pain, leg weakness, and urinary retention. Which step should come first?
- Outpatient MRI within 2 weeks
- Start NSAIDs and reassess
- High-dose IV dexamethasone and emergent whole-spine MRI (Correct answer)
- Bone scan
Correct answer: High-dose IV dexamethasone and emergent whole-spine MRI
Suspected malignant spinal cord compression is an emergency. Glucocorticoids should be given promptly and an urgent MRI of the entire spine obtained, followed by radiation and/or surgery. Neurologic status at treatment strongly predicts outcome.
Question 5: A patient on chemotherapy has a temperature of 38.5°C and an ANC of 300/µL, and is hemodynamically stable. Which is the most appropriate empiric therapy?
- Oral azithromycin
- IV vancomycin alone
- Await blood cultures before any antibiotics
- IV cefepime (Correct answer)
Correct answer: IV cefepime
Febrile neutropenia needs immediate empiric antipseudomonal beta-lactam monotherapy, such as cefepime, piperacillin-tazobactam, or meropenem, after cultures are drawn. Vancomycin is added only for specific indications.
Question 6: A patient with squamous cell lung carcinoma has a calcium of 13.8 mg/dL and a suppressed PTH. What is the most likely mechanism?
- Ectopic PTH secretion
- Tumor production of PTH-related peptide (PTHrP) (Correct answer)
- Excess 1,25-dihydroxyvitamin D production
- Primary hyperparathyroidism
Correct answer: Tumor production of PTH-related peptide (PTHrP)
Humoral hypercalcemia of malignancy from PTHrP is the most common mechanism of malignancy-associated hypercalcemia and is classic for squamous cell carcinomas. Endogenous PTH is suppressed. Calcitriol-mediated hypercalcemia is typical of lymphomas.