Neoplasia USMLE Step 1 Practice Question
A 45-year-old woman presents to her physician after discovering a palpable left breast mass. She has a significant family history notable for early-onset breast cancer in her mother (age 38) and maternal grandmother (age 42), as well as ovarian cancer in an aunt. Physical examination reveals a firm, fixed 2-cm mass in the upper outer quadrant of the left breast. Mammography and biopsy confirm invasive ductal carcinoma with ER+, PR+, HER2− immunophenotype. Genetic testing reveals a BRCA1 mutation. Which of the following best explains why BRCA1 mutation carriers have markedly elevated lifetime risk for breast and ovarian malignancies?
Answer choices
- AGermline mutations in mismatch repair genes that cause microsatellite instability and accumulation of secondary mutations
- BHaploinsufficiency of a tumor suppressor gene required for homologous recombination DNA repairCorrect answer
- CConstitutive activation of RAS/MAPK signaling pathways leading to uncontrolled cellular proliferation
- DSomatic amplification of HER2 and other oncogenes on chromosome 17q
- EEpigenetic silencing of estrogen receptor genes resulting in hormone-independent growth
- FLoss of p53-mediated apoptosis due to mutations in the TP53 gene
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