BRCA breast cancer gene: One of several genetic mutations linked to breast cancer and ovarian cancer. There is now convincing evidence that every woman with a BRCA mutation is at high risk for breast cancer, irrespective of whether she has a family history of breast cancer or not. By age 80, a woman with a BRCA mutation has about an 80% chance of developing breast cancer. BRCA1 and BRCA2 increase the risk of ovarian cancer 54% and 23%, respectively. Mutations in BRCA1 or BRCA2 account for 5-10% of all breast cancer which translates into 10-20,000 new cases of breast cancer in the US and many more around the world every year.
The BRCA mutations appear to cause breast cancer at an earlier age in younger generations. The culprit may be estrogen, which is rising with the epidemic of obesity. Pregnancy is protective. BRCA mutation carriers who have children develop breast cancer as a rule later in life than those who never had children. (That finding is true for all types of breast cancer, not just cases caused by BRCA mutations.)
It is recommended that women with BRCA mutations have frequent mammograms and MRI and ultrasound scans to detect breast cancer early. They may also be advised to take the drug tamoxifen to reduce the breast cancer risk. Some women with BRCA mutations avoid breast cancer by having their breasts preventively removed. Most BRCA carriers are also advised to have their ovaries removed after childbearing since there is currently no means of early detection for ovarian cancer. Removing the ovaries also helps to lower the risk of breast cancer.