Breast cancer is the most common cancer among women, excluding skin cancers.
The risk of breast cancer increases with age, with the majority of sporadic breast cancers occurring after menopause. Women who inherit a single mutated copy of either BRCA1 or BRCA2 have a sharply increased risk of breast cancer. Women with BRCA mutations who have been diagnosed with breast cancer are at risk of second breast tumors and ovarian cancer. Women with breast cancer and germline BRCA mutations also are at 10-fold increased risk of developing ovarian cancer. The risk of these second cancers may be a reason for considering BRCA1 and BRCA2 testing in women who are diagnosed with breast cancer and whose family history indicates hereditary breast and ovarian cancer.