Bilateral oophorectomy and risk of cancer in African American women.

PURPOSE: African American women are more likely to undergo hysterectomy, with or without bilateral oophorectomy, at younger ages than white women. It is well established that women who have a bilateral oophorectomy at younger ages are at reduced risk of breast cancer, and there is some evidence of an increased risk of colorectal and lung cancer.
METHODS: Using data from 44,514 women in the Black Women's Health Study, we prospectively investigated the relation of hysterectomy and oophorectomy to incidence of breast, colorectal, and lung cancer and to mortality from cancer. Hazard ratios (HRs) and 95 % confidence intervals (CIs) were estimated using Cox proportional hazards regression with control for confounding factors.
RESULTS: During 16 years of follow-up, hysterectomy alone, relative to no hysterectomy, was not associated with risk of breast, lung, or colorectal cancer. Bilateral oophorectomy, relative to hysterectomy with ovarian conservation, was inversely associated with risk of estrogen receptor-positive (ER+) breast cancer (HR 0.62; 95 % CI 0.45-0.85) but not with ER-negative breast cancer; age at surgery and menopausal hormone use did not modify the associations. HRs for the association of bilateral oophorectomy with incidence of colorectal and lung cancer were nonsignificantly increased for women who had surgery before age 40 years and had used menopausal hormones for less than 2 years (HR 1.65; 95 % CI 0.73-3.73 for colorectal cancer and HR 1.71; 95 % CI 0.68-4.31 for lung cancer). Bilateral oophorectomy was not associated with cancer mortality.
CONCLUSIONS: Bilateral oophorectomy was associated with reduced risk of ER+ breast cancer regardless of age at surgery and use of menopausal hormones. There were nonsignificant increases in risk of colorectal and lung cancer for women with oophorectomy at younger ages and short duration of menopausal hormone use.