BRCA 1 & 2 genes
The average woman (without an inherited breast cancer gene abnormality) in the United States has about a 12% risk of developing breast cancer over a 90-year life span. In contrast, women who have an abnormal BRCA1 or BRCA2 gene have up to an 85% risk of developing breast cancer by age 70. Women with BRCA1 and BRCA2 abnormalities are also at increased risk of developing ovarian cancer. The lifetime risk is about 55% for women with BRCA1 mutations and about 25% for women with BRCA2 mutations.
The BRCA gene test is a blood test that uses DNA analysis to identify changes (mutations) in either one of two breast cancer susceptibility genes — known as BRCA1 or BRCA2. Genetic counseling also is part of the BRCA gene test process. After having a BRCA gene test performed, you learn whether you carry an inherited BRCA gene mutation and receive an estimate of your personal risk of breast cancer and ovarian cancer.
The BRCA gene test is a type of genetic test that’s possible only for certain diseases that run in families, and it’s offered only to women who are at very high risk of breast cancer and ovarian cancer based on personal or family history. The BRCA gene test isn’t routinely performed on women at average risk of these cancers.
Having a BRCA gene mutation is rare, occurring only in about one in 1,000 people. Inherited BRCA gene mutations are responsible for less than 5 to 10 percent of breast cancers and about 10 to 15 percent of ovarian cancers. The majority of these cancers occur sporadically and aren’t inherited.
Sources: Mayo clinic and breastcancer.org