Oral contraceptives and neoplasia of the ovary

Epidemiologic literature on oral contraceptives in relation to primary ovarian cancer is reviewed. Compared to women who have never used oral contraceptives, women who have ever taken oral contraceptives have about a 30% reduction in risk for epithelial ovarian cancer, and five or more years of use is associated with a 50% reduction in risk. The protective effect of oral contraceptives persists for ten or more years after use is discontinued, and becomes apparent several years after beginning use. Effects of oral contraceptives are similar for malignant and borderline malignant epithelial ovarian cancer. Reduced risks among oral contraceptive users have been observed for all major histologic subtypes of epithelial ovarian cancer, and for women from developed and developing countries. Risk estimates for epithelial ovarian cancer in relation to oral contraceptive use stratified by age at diagnosis or parity are not uniform across studies. No consistent protective effect is apparent for non-epithelial ovarian tumors or benign ovarian tumors, including teratomas and cystadenomas, although limited data are available on the relationship between oral contraceptives and these neoplasms. Several areas for future research are described.