Polycystic ovary syndrome increases the risk of endometrial cancer in women aged less than 50 years: an Australian case–control study

Although polycystic ovary syndrome (PCOS) is commonly cited as a risk factor for endometrial cancer, supporting epidemiological evidence is currently very limited. Our aim was to assess the associations between PCOS, PCOS symptoms, and risk of endometrial cancer in women aged less than 50 years. Data came from a national population-based case–control study in Australia. Cases with newly diagnosed histologically confirmed endometrial cancer were identified through treatment clinics and cancer registries Australia wide. Controls were randomly selected from the national electoral roll. Women were interviewed about their reproductive and medical history, including self-reported PCOS, and lifestyle. Current analyses were restricted to women aged under 50 (156 cases, 398 controls). We estimated odds ratios (OR) using logistic regression to adjust for confounding factors. Women with PCOS had a fourfold increased risk of endometrial cancer compared to women without PCOS (OR 4.0, 95% CI 1.7–9.3). This association was attenuated when additionally adjusted for body mass index (OR 2.2, 95% CI 0.9–5.7). Risk was slightly greater when restricted to Type I cancers. PCOS symptoms including hirsutism and very irregular periods were significantly associated with endometrial cancer risk. These data extend existing findings, including adjustment for confounders, suggesting PCOS is a risk factor for endometrial cancer.