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Introduction
BRCA Testing
The breast cancer (BRCA) gene test is a blood test to check for specific changes (mutations) in genes called BRCA1 and BRCA2 that are associated with an increased risk of developing breast cancer. A positive result for the BRCA1 or BRCA2 gene indicates a 36% - 85% increased risk of developing breast cancer, but does not predict whether breast cancer will actually occur. BRCA gene mutations occur in 5-10% of women with breast cancer, and are most frequently identified in women under age 50. Young patients with BRCA 1 mutations have an approximately 20% chance of developing breast cancer before age 40 and an 80% chance before age 70. In young breast cancer patients of Ashkenazi descent, 20% have BRCA 1 gene mutations and 2.6% have BRCA 2 mutations.
This test may be useful for people with a strong family history of breast cancer and sometimes for those who already have the disease. It is used to help women (and men) with a strong family history of breast cancer find out if their chance is high enough to increase screening efforts or to consider prevention measures-such as taking medicine (Tamoxifen), having a preventive mastectomy, oophorectomy (removal of the ovaries), or other measures.
It is important to remember that testing for these genetic mutations is not simple. Thousands of mutations exist and current genetic tests are not perfect. Researchers are working to improve the sensitivity and specificity of these tests.
