A long-term, multicenter study has shown that the reduction in breast and ovarian cancer risk resulting from oophorectomy—the removal of the ovaries and fallopian tubes in women at genetically high risk for these diseases—varies according to the type of genetic mutation present. Specifically, women with mutations in the BRCA1 gene have a greater reduction in ovarian cancer risk following the surgery, while those with BRCA2 mutations have a larger decrease in breast cancer risk. The study results were presented in Atlanta at the American Society of Clinical Oncology annual meeting.

"This study provides the strongest confirmation to date that risk-reducing removal of the ovaries and fallopian tubes prevents both breast and ovarian cancers in women with mutations in BRCA1 and BRCA2," said Noah D. Kauff, MD, assistant attending physician at Memorial Sloan-Kettering Cancer Center and lead author of the study. "This is also the first study to suggest that removal of the ovaries may have different effects on BRCA1 and BRCA2 mutation carriers."

Previous studies have shown that the surgery, called "risk-reducing salpingo-oophorectomy" (RRSO), lowers the risk of breast and ovarian cancers in women at high risk for this disease due to BRCA mutations, but those studies were limited by short follow-up time and did not analyze women by what type of BRCA mutation they had.

Current Study Protocol

In this study, researchers compared the incidence of breast and ovarian cancers between 561 women 30 years of age or older with a BRCA1 or BRCA2 mutation who had RRSO surgery, and 325 women with these mutations who did not have the surgery. Participants were enrolled in the study beginning in November 1994 and were followed through November 2005.

After a median of 40 months of follow-up, RRSO reduced breast cancer risk by 47% and ovarian cancer risk by 89% in the group as a whole. Further analysis showed that the surgery reduced breast cancer risk in women with a BRCA2 mutation by 72%, compared with only 39% among those with a BRCA1 mutation. The surgery reduced ovarian cancer risk in women with a BRCA1 mutation by 87%. No ovarian cancers were observed after surgery in women with BRCA2 mutations. The overall incidence of ovarian cancer, however, was much lower in this group, with only two cases observed in women with BRCA2 mutations who elected surveillance instead of RRSO.