Proanthocyanidins and other flavonoids in relation to endometrial cancer risk: a case–control study in Italy

BACKGROUND: Because of their antioxidant and antimutagenic properties, flavonoids may reduce cancer risk. Some flavonoids have antiestrogenic effects that can inhibit the growth and proliferation of endometrial cancer cells. METHODS: In order to examine the relation between dietary flavonoids and endometrial cancer, we analysed data from an Italian case–control study including 454 incident, histologically confirmed endometrial cancers and 908 hospital-based controls. Information was collected through a validated food-frequency questionnaire. We applied data on food and beverage composition to estimate the intake of flavanols, flavanones, flavonols, anthocyanidins, flavones, isoflavones, and proanthocyanidins. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated from multiple logistic regression models conditioned on age and study centre and adjusted for major confounding factors. RESULTS: Women in the highest quartile category of proanthocyanidins with ⩾3 mers vs the first three quartile categories had an OR for endometrial cancer of 0.66 (95% CI=0.48–0.89). For no other class of flavonoids, a significant overall association was found. There was a suggestion of an inverse association for flavanones and isoflavones among women with body mass index <25 kg m(−2), and, for flavanones, among parous or non-users of hormone-replacement therapy women. CONCLUSION: High consumption of selected proanthocyanidins may reduce endometrial cancer risk.