Factors related to inflammation of the ovarian epithelium and risk of ovarian cancer

Previous epidemiologic observations consistently suggest that suppression o f ovulation, tubal ligation, and hysterectomy reduce the risk of ovarian ca ncer and that perineal talc use increases the risk. We examined these and o ther risk factors in the context of a new hypothesis: that inflammation may play a role in ovarian cancer risk. Ovulation entails ovarian epithelial i nflammation; talc, endometriosis, cysts, and hyperthyroidism may be associa ted with inflammatory responses of the ovarian epithelium; gynecologic surg ery may preclude irritants from reaching the ovaries via ascension from the lower genital tract. We evaluated these risk factors in a population-based case-control study. Cases 20-69 years of age with a recent diagnosis of ep ithelial ovarian cancer (767) were compared with community controls (1367). We found that a number of reproductive and contraceptive factors that supp ress ovulation, including gravidity, breast feeding, and oral contraception , reduced the risk of ovarian cancer. Environmental factors and medical con ditions that increased risk included talc use, endometriosis, ovarian cysts , and hyperthyroidism. Gynecologic surgery including hysterectomy and tubal ligation were protective. Tubal ligation afforded a risk reduction even 20 or more years after the surgery. The spectrum of associations provides sup port for the hypothesis that inflammation may mediate ovarian cancer risk.