Both breast and ovarian cancer can be caused by mutations in the BRCA1 (breast cancer gene 1) and BRCA2 (breast cancer gene 2) genes. Women with a family history of breast and ovarian cancer, or a personal history for either, particularly if diagnosed before age 50, should be aware of increased risk for the other. Women who have had breast cancer before the age of 50 are twice as likely to develop ovarian cancer, as are women who have not (National Cancer Institute – What You Need To Know About Ovarian Cancer, 1998).  Additionally, ovarian cancer has also been linked to colorectal cancer and uterine cancer (via different genes).