BRCA1 or BRCA2 gene mutations are known to be associated with breast and ovarian cancers. This study analyzes the age-specific risk of breast and ovarian cancer for BRCA1/2 mutation carriers from a large prospective cohort. A total of 9,856 women, including 6,036 BRCA1 and 3,820 BRCA2 carriers (5046 unaffected and 4810 with breast or ovarian cancer or both at baseline), in Australia, the United States and Europe are evaluated. The results from this study indicate that the risk of developing breast cancer by the age of 80 is 72% for BRCA1 and 69% for BRCA2, respectively; the risk of developing ovarian cancer by the age of 80 is 44% for BRCA1 and 17% for BRCA2, respectively. The risk of breast cancer increases with family history, especially among first- and second-degree relatives for both BRCA1 (1.99 times higher) and BRCA2 (1.91 times higher) carriers. However, in ovarian cancer, the risk of BRCA1 carriers with family history is not significantly different; there are no conclusive results in BRCA2 carriers due to the small sample size. Risk of breast cancer increases if the BRCA1 and BRCA2 mutations are located within the region as the study reported. These results indicate that family history and mutation position are important in risk assessment.
Kuchenbaecker KB, Hopper JL, Barnes DR, et al., JAMA, 2017