Long-term dietary heme iron and red meat intake in relation to endometrial cancer risk

Background: Heme and total iron, present in meat, have been hypothesized to promote carcinogenesis. Few prospective studies have examined the associations between intakes of heme and total iron, types of meat, and endometrial cancer risk. Objective: We evaluated the associations between intakes of heme and total iron, types of meat, and risk of endometrial cancer in a large cohort of women. Design: Among 60,895 women in the Swedish Mammography Cohort, 720 endometrial cancer cases were confirmed during 21 y of follow-up. RRs and 95% CIs were calculated by Cox proportional hazards models. Results: A comparison of the highest with the lowest quartile showed a 20-30% higher risk of endometrial cancer for higher intakes of heme iron (RR: 1.24; 95% CI: 1.01, 1.53 for >= 1.63 compared with <0.69 mg/d), total iron (RR: 1.31; 95% CI: 1.07, 1.61 for >= 15.09 compared with <12.27 mg/d), and liver (RR: 1.29; 95% CI: 1.06, 1.56 for >= 100 compared with <100 g/wk). No statistically significant associations were observed between intakes of red and processed meats and endometrial cancer risk. RRs did not greatly differ when we stratified by BMI, parity, and intakes of alcohol, vitamin C, or zinc or when we excluded patients with diabetes. Conclusions: Our study suggests a modest positive association between heme iron, total iron, and liver intakes and endometrial cancer risk; no statistically significant associations were observed for intakes of other red and processed meats and endometrial cancer risk. The Swedish Mammography Cohort was registered at clinicaltrials.gov as NCT01127698. Am J Clin Nutr 2012;96:848-54.