Ovarian cancer and genetic susceptibility in relation to the BRCA1 and BRCA2 genes. Occurrence, clinical importance and intervention.
The Nordic countries have the highest incidences of ovarian cancer in the world (around 15 cases per 100,000 women). We have conducted a review of the recent literature with focus on the Nordic countries, on genetic susceptibility to ovarian cancer, and the clinical implications in relation to the BRCAI and BRCA2 genes. One of the strongest risk factors for ovarian cancer is a family history of ovarian and/or early-onset breast cancer. It is thought that germline mutations in BRCA1/2 might be responsible for as much as 10% of all ovarian cancer cases and all families containing either multiple case, site-specific ovarian cancer cases or breast and ovarian cancers together. Data from several international studies suggest that the lifetime risk of ovarian cancer in a BRCA 1 mutation carrier can vary from 18 to 56% and from 14 to 27% in a BRCA2 carrier, depending on the presence/absence of a family history of the disease. Genetic evaluation and testing is used in many countries to identify families with BRCA1/2 mutations. Once a mutation has been identified, genetic counseling and testing can be offered to unaffected family members. Prophylactic oophorectomy in unaffected mutation carriers will eliminate the risk of ovarian cancer, although there is a slight residual risk of peritoneal cancer. During oophorectomy, the Fallopian tube should also be removed. If a woman does not want prophylactic oophorectomy, then tubal ligation or oral contraceptive use can be considered as these have been shown to reduce ovarian cancer risk also in mutation carriers.