Breast Cancer Prevention for Mutation Carriers

In 1994 and 1995 respectively, the BRCA1 and BRCA2 genes were discovered. For women who carry a mutation in one of these genes, the risk of developing breast cancer is up to 87% by the age of 70, and the risk of developing ovarian cancer is up to 60%. This can be compared to average cancer risks in the general population; an 11% lifetime risk of developing breast cancer and a 1.5% risk of developing ovarian cancer. There are several cancer prevention options that women with a BRCA1 or BRCA2 mutation may consider with varying levels of protection. The three main options are prophylactic mastectomy, prophylactic oophorectomy, and chemoprevention (tamoxifen). Prophylactic mastectomy offers the greatest protection against breast cancer, decreasing risk by approximately 90% to 95%. Tamoxifen (chemopreventive drug) offers approximately a 50% reduction in breast cancer risk in high-risk individuals, but there is limited evidence on the effectiveness in women with a BRCA mutation.6 However, prophylactic oophorectomy offers a significant reduction in the risk of both breast cancer (approximately 50%) and ovarian cancer (approximately 90%) in women with a BRCA mutation. The ultimate benefit of genetic testing for BRCA1 and BRCA2 is to identify high-risk individuals prior to the diagnosis of cancer so that the risk of cancer can be substantially decreased. However, this can only be realized if women are aware of their BRCA status, are cognizant of recommended risk reduction strategies, and thus elect for the uptake of a cancer prevention option.