The genes that are most commonly involved in Hereditary Breast and Ovarian Cancer (HBOC) are BRCA1 and BRCA2. Identified in 1994 and 1995, these genes are named for their link to breast (BR) cancer (CA), but we know that they are also linked to ovarian cancer risk as well as other cancers. BRCA1 and BRCA2 are tumor suppressor genes that have a usual role in our body of providing instructions on repairing damage and preventing cancer. When a family has an inherited mutation in BRCA1 or BRCA2, this leads to an increase in cancer risk. Not every man or woman who has inherited a mutation in the BRCA1 or BRCA2 gene will develop cancer, but people who have a mutation do have an increased chance of developing cancer, particularly cancer of the breasts or ovaries.

While breast and ovarian cancers are the most common cancers diagnosed in people with BRCA1 and BRCA2 mutations, the risk of some other cancers is also increased. Men with BRCA1 and BRCA2 have a higher risk of early-onset (under age 65) prostate cancer than the average man. Other cancers seen at increased rates, particularly in individuals with BRCA2 mutations, include pancreatic cancer and melanoma. Since these cancers are rarer, the overall risk of pancreatic cancer and melanoma for men and women with a BRCA2 mutation is still low. Researchers are continuing to find new genes that are involved in hereditary breast and/or ovarian cancer, and our knowledge about BRCA1 and BRCA2 is helping families with mutations in those genes as well.