Objective: To estimate ovarian and peritoneal cancer rates after hysterectomy with and without salpingo-oophorectomy for benign conditions.
Methods: All patients after hysterectomy for benign disease from 1988 to 2006 in Kaiser Permanente Northern California, an integrated health organization. Incidence rates per 100,000 person-years were calculated.
Results: Of 56,692 patients, the majority (54%) underwent hysterectomy with bilateral salpingo-oophorectomy; 7% had hysterectomy with unilateral salpingo-oophorectomy, and 39% had hysterectomy alone. There were 40 ovarian and eight peritoneal cancers diagnosed during follow-up. Median age at ovarian and peritoneal cancer diagnosis was 50 and 64 years, respectively. Age-standardized rates (per 100,000 person-years) of ovarian or peritoneal cancer were 26.7 (95% confidence interval [CI] 16-37.5) for those with hysterectomy alone, 22.8 (95% CI 0.0-46.8) for hysterectomy and unilateral salpingo-oophorectomy, and 3.9 (95% CI 1.5-6.4) for hysterectomy and bilateral salpingo-oophorectomy. Rates of ovarian cancer were 26.2 (95% CI 15.5-37) for those with hysterectomy alone, 17.5 (95% CI 0.0-39.1) for hysterectomy and unilateral salpingo-oophorectomy, and 1.7 (95% CI 0.4-3) for those with hysterectomy and bilateral salpingo-oophorectomy. Compared with women undergoing hysterectomy alone, those receiving an unilateral salpingo-oophorectomy had a hazard ratio (HR) for ovarian cancer of 0.58 (95% CI 0.18-1.9) and those undergoing bilateral salpingo-oophorectomy had an HR of 0.12 (95% CI 0.05-0.28).
Conclusions: The removal of both ovaries decreases the incidence of ovarian and peritoneal cancers. Removal of one ovary might also decrease the incidence of ovarian cancer but warrants further investigation.
Level of evidence: II.