Key Points

Most hereditary cancer predisposition syndromes are inherited in an autosomal dominant pattern.

Although most families with a history suggestive of hereditary ovarian cancer do not have a currently recognizable syndrome, a significant proportion is due to one of two known syndromes, hereditary breast and ovarian cancer (HBOC) or hereditary nonpolyposis colorectal cancer (HNPCC).

Features suggestive of HBOC include premenopausal breast cancer, ovarian cancer, and male breast cancer. Families with a significant history of young-onset colorectal or endometrial cancer are suggestive of HNPCC.

BRCA1 and BRCA2 are two genes responsible for HBOC, and they appear to function as tumor suppressor genes.

Mutations in BRCA1 and BRCA2 have a high penetrance, conferring a lifetime risk of ovarian cancer of between 20% and 65%. As with breast cancer, BRCA1 mutations are associated with a higher risk of ovarian and primary peritoneal cancer and earlier age of onset compared with BRCA2 mutations.

The precise factors dictating which mutation carriers will develop cancer are unknown and are thought to depend on both genetic and environmental risk modifiers.

Genetic testing for BRCA1 and BRCA2 is clinically available; for most families this involves full sequencing of both genes.

Four genes have been associated with HNPCC thus far, and clinical genetic testing is available for all of these genes.

Interventions in women who carry BRCA1, BRCA2, or HNPCC mutations include intensive cancer screening, chemoprevention, and prophylactic surgery. In BRCA1 and BRCA2 mutation carriers, prophylactic bilateral salpingo-oophorectomy has been shown to reduce the risk of ovarian cancer by 80% to 90% when compared with gynecologic surveillance to detect early-stage ovarian cancer. In the United States, bilateral salpingo-oophorectomy is considered the standard of care. Although the predominant feature of HNPCC is an increased risk of colorectal cancer—and to a lesser extent endometrial cancer—it is often forgotten that this syndrome is also associated with a 10% lifetime risk of ovarian cancer.

Patients whose personal or family history is suggestive of HBOC or HNPCC should be referred for genetic counseling and discussion of screening and preventive strategies.

DNA banking by women with ovarian cancer that is not explained by current genetic technology is also an option that should be discussed and undertaken by some families.

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