Infertility-Associated Endometrial Cancer Risk May Be Limited to Specific Subgroups of Infertile Women

Data from previous studies suggest that infertility is a risk factor for endometrial cancer. We used data from the Cancer and Steroid Hormone Study to further characterize this relationship. The subject group comprised 399 women ages 20–54 with newly diagnosed epithelial endometrial cancer ascertained through six cancer registries. The control group comprised 3040 women in the same age range selected by random-digit telephone dialing from the same geographic areas where cancer patients resided. Compared with women who reported no fertility problem, women with physician-diagnosed infertility who had reported at least 2 years of infertility had an odds ratio for endometrial cancer, adjusted for age, of 1.7 (95% confidence interval 1.1–2.6). Women who reported infertility resulting from ovarian factors had an adjusted odds ratio of 4.2 (95% confidence interval 1.7–10.4). These results suggest that factors such as anovulation may explain much of the increased risk of endometrial cancer found among subgroups of infertile women.