Having a BRCA mutation means you have a likelihood of 45% to 85% for developing breast cancer in your lifetime, along with a 10% to 46% chance of ovarian cancer. The probability of breast cancer among the general population is about 12%.

The rate of germline BRCA1 or 2 mutations in ovarian cancer patients without a family history or breast or ovarian cancer is low. However, in women with additional family members affected, the prevalence is considerably higher than previously reported.

Breast cancers with harmful BRCA1 variants are more likely to be "triple-negative cancers" (that is, the breast cancer cells do not have estrogen receptors, progesterone receptors, or large amounts of HER2/neu protein) than sporadic breast cancers or breast cancers with harmful BRCA2 variants.

In both BRCA1 and BRCA2, the graphs show no significant increased risk of ovarian cancer until age 45. If you have a BRCA1 gene mutation, risk increases at age 45-49 and again at age 55-59. Risk increases later if you have a BRCA2 gene mutation.