Because women with the BRCA1 or 2 mutations are at high (15 to 54 percent) lifetime risk of developing ovarian cancer, they are frequently advised to have a preventive bilateral oophorectomy (removal of the fallopian tubes and ovaries) by age 35. To obtain an accurate estimate of risk reduction as a result of surgery, researchers followed 1828 women gene carriers for about 3.5 years until they were either diagnosed with ovarian, fallopian tube or peritoneal cancer, died, or had their most recent medical follow-up.

Thirty percent had both ovaries and fallopian tubes removed prior to enrollment; 27 percent had the surgery while enrolled, and 43 percent did not. The results showed that until age 75, women with the BRCA1 mutation whose ovaries remain intact have a 62 percent risk of ovarian cancer compared to 18 percent for the BRCA2 carriers. But women who underwent oophorectomy had an 80 percent reduction in their risk of reproductive cancers and a four percent risk reduction of peritoneal cancer. Carriers with a history of breast cancer had a higher risk of reproductive cancers compared to those who had no breast cancer history. Although oophorectomy is usually advised when women are in their mid-thirties, the authors said that in order to preserve fertility, they would “consider doing the procedure closer to menopause in BRCA2 carriers without increasing ovarian cancer risk, but this would not provide optimal protection against breast cancer.” In general, having an oophorectomy before menopause reduces the risk of breast cancer by about one-half. This is the first large study of its kind, and was published in a recent issue of the Journal of the American Medical Association.