Findings from an international study of over 6000 women with a BRCA1 mutation and almost 4000 women with a BRCA2 mutation followed for an average of 5 years were recently published.1 Results showed the risk of breast cancer by age 80 was ~70% for both BRCA1 and BRCA2 carriers. Rates of breast cancer increased until age 30-40 in BRCA1 carriers and 40-50 in BRCA2 carriers, after which they remained constant over time to age 80. Risk of ovarian cancer by age 80 was 44% among BRCA1 carriers and 17% among BRCA2 carriers. Among women with a prior breast cancer diagnosis, the risk of developing another new breast cancer in the other breast (called “contralateral breast cancer”) after 20 years was 40% for BRCA1 carriers and 26% for BRCA2 carriers. Overall, the risk of breast cancer was higher in individuals who had more relatives with breast cancer. Consistent with findings published by Rebbeck et al. in 2015 in JAMA, there were certain locations of the gene mutation that presented a higher risk for breast cancer2 – specifically, risks of breast cancer were higher for: 1) BRCA1 if the mutation was outside the region between c.2282-c.4071 and 2) BRCA2 if the mutation was outside the region between c.2831-c.6401. Ultimately, findings from the current study provide information to better predict cancer risks based on family history and mutation location, which may contribute to developing and improving personalized cancer risk management for women with mutations in these genes.
1Kuchenbaecker et al. JAMA. 2017 Jun 20;317(23):2402-2416. PMID: 28632866.
2Rebbeck et al. JAMA 2015 Apr 7;313(13):1347-61. PMID: 25849179.