Role of reproductive factors on the risk of endometrial cancer.

We analyzed the role of reproductive factors on the risk of endometrial cancer using data from a case-control study conducted in Italy. Cases were 752 women with histologically confirmed endometrial cancer < 75 years of age. Controls were 2,606 patients < 75 years of age admitted for acute, non-gynecological non-hormone-related, non-neoplastic conditions to the same network of hospitals where cases had been identified. In comparison with nulliparae, the risk of endometrial cancer tended to be lower in parous women, and the estimated multivariate odds ratios (ORs) were 0.9, 0.8 and 0.7, respectively, for women reporting 1, 2 and 3 or more births (chi(2)(1) trend and 10.21). In comparison with women reporting no induced abortion, the ORs of endometrial cancer were 0.6 in women reporting 1 and 0.4 in those reporting 2 or more induced abortions. When considering parous women only, in comparison with women reporting their last birth 20 years before or longer, the ORs of endometrial cancer were 0.6 in those reporting their last birth 10-19 years before and 0.3 in those reporting their last birth < 10 years before. Our results confirm and further quantify a protective role of pregnancy on the risk of endometrial cancer and provide insights on the time-risk relationship between pregnancy and cancer of corpus uteri.