A 38-year-old BRCA1-positive woman elects risk-reducing bilateral salpingo-oophorectomy (RRSO) and bilateral prophylactic mastectomy. Which statement best describes the risk-reduction achieved by prophylactic mastectomy in BRCA1 carriers?
- A Reduces breast cancer risk by approximately 90–95% ✓
- B Eliminates breast cancer risk entirely
- C Reduces breast cancer risk by approximately 50%
- D Risk reduction is equivalent to chemoprevention with tamoxifen
Correct answer: A. Reduces breast cancer risk by approximately 90–95%
Explanation
Prophylactic bilateral mastectomy in BRCA1/2 carriers reduces the lifetime risk of breast cancer by approximately 90–95%, but residual breast tissue cannot be completely excised even with nipple-sparing or skin-sparing mastectomy, so a small residual risk remains. It does not eliminate risk entirely (option B is incorrect). Tamoxifen chemoprevention in BRCA carriers reduces oestrogen receptor-positive risk by ~50%, far less than mastectomy. RRSO also reduces breast cancer risk (~50%) particularly in BRCA2 carriers.
Reference: Bailey & Love's Short Practice of Surgery, 27th ed.
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Written and medically reviewed by the StethoPrep medical team.