Clinical Question: Is prophylactic bilateral salpingo-oophorectomy (BSO) effective for reducing the risk of ovarian, fallopian tube, and peritoneal cancers in high-risk women?

Setting: Population-based

Study Design: Nonrandomized controlled trial

Synopsis: Women with a mutation in theBRCA1 orBRCA2 gene are at an increased risk of cancers of the ovary, fallopian tube, and peritoneum. The effectiveness of prophylactic BSO to prevent these cancers is uncertain. The investigators identified 1,828 women known to carry aBRCA1 orBRCA2 mutation from an international registry of 32 centers in Canada, the United States, Europe, and Israel. Patients initially free of ovarian cancer were monitored from the date of study entry until a diagnosis of ovarian cancer, fallopian tube cancer, peritoneal cancer, death, or the date of most recent evaluation. Final diagnoses were confirmed by review of medical records and pathology reports.

The mean age of the cohort at study entry was 47.3 years (range: 30 to 74 years). Of the 1,828 participants, 555 (30.4 percent) underwent prophylactic BSO before study entry, and an additional 490 (38.5 percent of remaining patients) underwent the procedure during the follow-up period. Women who did and who did not undergo BSO were similar with regard to history of breast cancer, parity, oral contraceptive use, and hormone therapy. All women underwent periodic follow-up for a mean of 3.5 years. Among women with intact ovaries, 32 cancers were detected (29 ovarian, two fallopian tube, and one primary peritoneal). Of the 490 women undergoing prophylactic BSO during the follow-up period, 11 had cancer at the time of surgery. Seven additional women undergoing the procedure presented with primary peritoneal cancer during follow-up.

A multivariate statistical model controlling for age, country of origin, gene type, history of breast cancer, oral contraceptive use, history of breastfeeding, and parity estimated an 80 percent reduction in the risk of cancer associated with prophylactic BSO (hazard ratio = 0.20; number needed to treat to prevent one additional cancer every 3.5 years = 36; 95% confidence interval, 31 to 70).

Bottom Line: BSO is effective for reducing the risk of ovarian, fallopian tube, and peritoneal cancers in high-risk women with a mutation in theBRCA1 orBRCA2 gene. Thirty-six women will need to undergo BSO to prevent one additional cancer every 3.5 years. It is important to inform women who are considering this procedure that recommendations are not based on a true randomized trial and that there is insufficient information on the effects of surgery on long-term morbidity and all-cause mortality. (Level of evidence: 2b)