Does tamoxifen reduce the risk of breast cancer in healthy women with a BRCA1 or BRCA2 mutation?[Scroll to bottom for answer]
The data are unclear. Although a meta-analysis found that BRCA1/2 mutation carriers with breast cancer reduced the risk of contralateral breast cancer by over 40%, very little data on primary prevention exist. The largest study in healthy women contained only 19 BRCA1/2 carriers (8 of women received tamoxifen), so the data showing risk reduction in BRCA2 but not BRCA1 carriers must be viewed with caution.
King MC, et al. Tamoxifen and breast cancer incidence among women with inherited mutations in BRCA1 and BRCA2: National Surgical Adjuvant Breast and Bowel Project (NSABP-P1) Breast Cancer Prevention Trial. JAMA 2001;286:2251.