Oophorectomy and hysterectomy and cancer incidence in the Cancer Prevention Study-II Nutrition Cohort.

OBJECTIVE To examine associations of simple hysterectomy and hysterectomy with bilateral salpingo-oophorectomy (BSO), relative to no surgery, with total and site-specific cancer risk in the Cancer Prevention Study-II Nutrition Cohort. METHODS We examined associations of hysterectomy with BSO and simple hysterectomy with total and site-specific cancer risk in 66,802 postmenopausal women from the Cancer Prevention Study-II Nutrition Cohort. RESULTS During a median follow-up of 13.9 years, 8,621 cancers were diagnosed. Hysterectomy with BSO performed at any age (1,892 cases), compared with no hysterectomy (n=5,586 cases), is associated with a 10% reduction in all cancers (relative risk [RR] 0.90, 95% confidence interval [CI] 0.85-0.96). This inverse association does not hold if the surgery occurred at ages 55 years or older (583 cases; RR 1.02, 95% CI 0.94-1.12). Hysterectomy with BSO (715 cases) was associated with a 20% reduction in breast cancer performed at any age (RR 0.80, 95% CI 0.73-0.88). Hysterectomy without BSO was associated with a deceased cancer risk only if performed at age 45 years or younger (541 cases; RR 0.88, 95% CI 0.80-0.97) and overall was associated with a decreased risk of breast cancer (419 cases; RR 0.86, 95% CI 0.76-0.96). CONCLUSION In a large prospective study, hysterectomy with BSO before age 55 years, relative to no surgery, is associated with a lower risk of total cancer. This information, particularly the lower risk in women younger than 45 years, should be considered in counseling women about ovarian management at the time of surgery. LEVEL OF EVIDENCE II.