A prospective study of reproductive factors and exogenous hormone use in relation to ovarian cancer risk among Black women.

Abstract

Extensive data in White women have linked oral contraceptive use, tubal ligation, and parity to reduced risk of ovarian cancer; results on postmenopausal female hormone use are mixed. Few studies, all of which are case-control studies, have been undertaken among Black women. The aim of the present study was to prospectively assess associations of reproductive factors and exogenous hormones with ovarian cancer among Black women. During follow-up from 1995 to 2013 in the Black Women's Health Study, a prospective cohort study, 115 incident cases of ovarian cancer were identified. Cox proportional hazards models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for the relation of the factors of interest to risk of ovarian cancer, with control for covariates. Oral contraceptive use was inversely associated with ovarian cancer risk: The HR for ≥10years of use relative to <1year was 0.50 (95% CI 0.30-0.98). For postmenopausal female hormone use, the HRs for ever use of estrogen with progestin and of estrogen alone were 1.37 (0.73-2.55) and 1.66 (0.90-3.07), respectively. The HRs for parity and tubal ligation were below 1.0, but were not statistically significant. Overall, the findings indicate that the relation of reproductive factors and exogenous hormone use to risk of ovarian cancer is similar among Black and White women. The results on estrogen-only supplements and estrogen with progestin supplements add to evidence from Whites, indicating that use of hormone supplements may be associated with increased risk of ovarian cancer.