Neoplasia USMLE Step 1 Practice Question
A 32-year-old woman presents to her gynecologist for evaluation of a palpable left breast mass discovered on self-examination. She reports her mother was diagnosed with breast cancer at age 38 and her maternal grandmother at age 45. The patient denies nipple discharge, skin changes, or constitutional symptoms. Vital signs are normal. Mammography and ultrasound confirm a 1.5 cm irregular mass with suspicious microcalcifications. Genetic counseling is arranged, and BRCA1 mutation testing returns positive. The patient is counseled regarding her significantly elevated lifetime risk of breast and ovarian cancer. Which of the following best explains the molecular mechanism by which BRCA1 mutations lead to increased cancer susceptibility?
Answer choices
- ALoss of BRCA1-mediated recruitment of mismatch repair complexes to sites of replication errors
- BImpaired homologous recombination repair of DNA double-strand breaks due to loss of BRCA1 scaffolding functionCorrect answer
- CDecreased expression of estrogen receptor-alpha, leading to unopposed estrogen signaling in breast tissue
- DEnhanced cellular proliferation through constitutive activation of growth factor receptor signaling
- EFailure to suppress telomerase expression and allow appropriate replicative senescence
- FLoss of p53-independent apoptotic mechanisms in response to oncogenic stress
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