Approximately 1 in 8 women (12.5%) in the general population will develop breast cancer during their lifetime. 1 in 65 women (1.5%) will be diagnosed with ovarian cancer.
Most cases of breast or ovarian cancer are sporadic, with no family history of cancer. However, 5-10% of breast cancer cases and about 15-20% of ovarian cancer cases are caused by hereditary predisposition. The features suggestive of hereditary cancer predisposition include: young age at diagnosis, several relatives affected with the same or related cancers, and multiple primary cancers in a single individual.
Many genes have been associated with an increased risk of breast and/or ovarian cancer. BRCA1 and BRCA2 are categorized as high risk genes, which means that they pose a greater than fourfold risk for developing breast and ovarian cancer. They can also pose a moderate risk for other types of cancer.
Pathogenic BRCA1 and BRCA2 variants (mutations) increase the lifetime risk for breast and ovarian cancer significantly over the general population risk. Women with pathogenic BRCA1 or BRCA2 variants are at 40-85% lifetime risk for breast cancer and 10-55% risk for ovarian cancer. Other associated cancers in women include fallopian tube carcinoma, primary peritoneal carcinoma and uterine serous carcinoma9-11. The lifetime risk for male breast cancer is approximately 6% in BRCA2 mutation carriers. The risk for other cancers in BRCA1/2 mutation carriers include prostate cancer in men and pancreatic cancer and melanoma in both men and women.