Contraception Methods, Beyond Oral Contraceptives and Tubal Ligation, and Risk of Ovarian Cancer

PURPOSE: Few studies have examined methods of contraception, beyond oral contraceptives (OCs) and tubal ligation, in relation to ovarian cancer risk. METHODS: Nine hundred two cases with incident ovarian/peritoneal/tubal cancer were compared with 1800 population-based control subjects. Women self-reported all methods of contraception by using life calendars. RESULTS: Each of the contraceptive methods examined reduced the risk of ovarian cancer as compared with use of no artificial contraception. Comparing ever versus never use, after adjustment for potentially confounding factors and all other methods of contraception, the methods of contraception that emerged as protective were OCs (adjusted odds ratio [adj OR] 0.75, 95% confidence interval [CI] 0.61-0.93); tubal ligation (adj OR 0.63, 95% CI 0.51-0.77); intrauterine devices (IUDs) (adj OR 0.75, 95% CI 0.59-0.95); and vasectomy (adj OR 0.77, 95% CI 0.61-0.99). Although for OCs and tubal ligation we found that the longer the duration of use, the greater the effect, for IUDs the pattern was reversed: significant protection occurred with short duration and progressively greater risk (albeit nonsignificant) was seen with longer duration of use. CONCLUSIONS: In the largest case-control study to date, a range of effective methods of contraception reduced the risk for ovarian cancer. OCs and tubal ligation reduced ovarian cancer risk with lower odds ratios with longer duration of use, whereas IUDs reduced risk overall, having the greatest impact with short duration of use. Ann Epidemiol 2011;21:188-196. (C) 2011 Elsevier Inc. All rights reserved.