Among women, the lifetime risk of developing breast cancer is 1 in 8, and this disease is the second leading cause of cancer deaths (after lung cancer). The presence of a mutation (inherited abnormality) in breast cancer susceptibility gene 1 or 2 (BRCA1/2) significantly increases the risk of breast and ovarian cancers.
BRCA mutations are autosomal dominant, meaning that they affect 50% of a gene carrier's offspring. These mutations are present only in 5% of women who are diagnosed as having breast cancer. However, their presence may increase the lifetime risk of breast cancer to between 40% and 85% and of ovarian cancer to between 20% and 50%. It also increases the risk of prostate and breast cancer in men who carry these genes.
The presence of a BRCA mutation is determined by genetic testing of a small blood sample. A woman should consider testing if in her family (such as mother, daughter, sister, grandmother, or aunt) there are any of the following:
3 relatives with breast cancer
2 relatives with breast cancer if at least 1 was diagnosed at age 50 years or younger
Cancer diagnosed in both breasts
Ovarian cancer, especially if there is more than 1 relative or there is also breast cancer in the family
Breast cancer in a male relative
Women who fit these criteria should consult with their doctor.
If a woman has a breast cancer removed that is triple-negative (a tumor with no estrogen, progesterone, or growth factor receptors) or she has Ashkenazi Jewish ancestors, she should consider genetic counseling and testing.
The risk of having a BRCA1/2 mutation in the general population is about 1 in 400. However, in the Ashkenazi Jewish population, it is 10 times higher (about 1 in 40). The individual risk of having a BRCA1/2 mutation can be assessed using one of many calculators accessible through your doctor.
Women with BRCA mutations should have early and regular breast examinations that may include mammograms and breast magnetic resonance imaging (MRI), as well as oncologic and genetic counseling. BRCA carriers may also consider undergoing prophylactic (preventive) mastectomy (breast removal) or ovariectomy (ovary removal). BRCA carriers who are considering childbirth may opt for egg-harvesting procedures with genetic testing to exclude BRCA mutations affecting their children.
Lumpectomy (resection of tumor from the breast) followed by chemotherapy and radiation is the usual treatment for BRCA1/2 carriers with breast cancer. But because of increased risk of second tumor development in the same or the other breast, a woman may consider prophylactic bilateral mastectomy, particularly if she is young and a carrier of BRCA1. Chemoprophylaxis (tamoxifen) and/or ovariectomy may decrease the risk of second breast cancer development.
With screening mammograms and breast MRIs, timely treatment, and/or prophylactic surgery, the life expectancy in BRCA carriers approaches the life span of noncarriers.
National Cancer Institutewww.cancer.gov/cancertopics/factsheet/Risk/BRCA
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Sources: National Cancer Institute at the National Institutes of Health
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Topic: CANCER GENETICS
Pluta RM, Golub RM. BRCA Genes and Breast Cancer. JAMA. 2011;305(21):2244. doi:10.1001/jama.305.21.2244