Dietary total antioxidant capacity in relation to endometrial cancer risk: a case–control study in Italy

To investigate the role of the overall antioxidant activity of diet, we estimated the relation between three dietary indices of total antioxidant capacity (TAC) and endometrial cancer risk We analyzed data from an Italian case-control study including 454 women with incident, histologically confirmed endometrial cancer, and 908 frequency-matched controls admitted to the same hospitals as cases for acute non-neoplastic conditions. A reproducible and valid food frequency questionnaire was used to assess subjects' habitual diet. TAC was measured using Italian food composition tables in terms of Ferric-reducing antioxidant power (FRAP), Trolox equivalent antioxidant capacity (TEAC), and total radical-trapping antioxidant parameter (TRAP). We computed odds ratios (OR) and corresponding 95 % confidence intervals (CIs) using conditional multiple logistic regression models, including terms for recognized endometrial cancer risk factors and total energy intake. TAC was inversely related to endometrial cancer risk with ORs for the highest versus the lowest quartile of 0.69 (95 % CI 0.47-1.00) for FRAP, 0.68 (95 % CI 0.46-0.99) for TEAC, and 0.68 (95 % CI 0.47-0.98) for TRAP. The relations appeared consistent in strata of selected risk factors and decreased when considering TAC without the contribution of coffee. Our findings suggest a favorable role of a diet high in TAC on endometrial cancer risk, which can be partially driven by coffee consumption.