A new prospective study has reported that prophylactic mastectomy is associated with reduced risk of breast cancer among BRCA1 and BRCA2 mutation carriers. In addition, prophylactic salpingo-oophorectomy (removal of the ovaries and fallopian tubes) is associated with lower risk of ovarian cancer, first diagnosis of breast cancer, all-cause mortality, breast cancer-specific mortality, and ovarian cancer-specific mortality among BRCA1/2 carriers. The study was designed to estimate reductions in breast and ovarian cancer risks and mortality resulting from prophylactic mastectomies and salpingo-oophorectomies. These surgeries are already widely used by BRCA1 and BRCA2 mutation carriers to reduce their risks of breast and ovarian cancer. The study was conducted at 22 centers in Europe and North America. Study participants included 2,482 women whose BRCA1 or BRCA2 mutations were confirmed by genetic testing between 1974 and 2008. The women were followed until year-end 2009.

None of the 247 women who underwent risk-reducing mastectomy were diagnosed with breast cancer during the follow-up period. On the other hand, 98 of the 1,372 women who did not have mastectomy were diagnosed with breast cancer. Compared with women who did not undergo prophylactic salpingo-oophorectomy, women who had salpingo-oophorectomy had a lower risk of ovarian cancer (including both those with prior breast cancer and those without prior breast cancer), and a lower risk of first diagnosis of breast cancer (for both BRCA1 mutation and BRCA2 mutation carriers). Compared with women who did not undergo prophylactic salpingo-oophorectomy, undergoing salpingo-oophorectomy was associated with lower mortality from all causes, death from breast cancer, and death from ovarian cancer.