Anthropometric factors and endometrial cancer risk: a systematic review and dose-response meta-analysis of prospective studies

Background: Greater body mass index (BMI) has been convincingly related to increased endometrial cancer risk, however, whether adiposity earlier in life or abdominal fatness is an independent risk factor and whether weight gain or greater height increases the risk is not clear. Methods: As part of the Continuous Update Project of the World Cancer Research Fund International, we conducted a systematic review and meta-analysis of prospective studies of the association between anthropometric measures and endometrial cancer risk and searched PubMed and several other databases up to February 2015. Summary relative risks (RRs) were calculated using a random-effects model. Results: Thirty prospective studies of BMI and endometrial cancer risk with 22 320 cases among 6 445 402 participants were included. The summary RR for a 5-unit increment was 1.54 [95% confidence interval (CI) 1.47-1.61, I-2 = 81%]. Although the test for non-linearity was significant, Pnon-linearity < 0.0001, and the curve was steeper within the overweight and obese BMI ranges, there was evidence of increased risk even within the high normal BMI range. The summary RR was 1.45 (95% CI 1.28-1.64, I-2 = 76%) per 5 BMI units for BMI in young adulthood, 1.18 (95% CI 1.14-1.23, I-2 = 67%) per 5 kg increase of weight, and 1.16 (95% CI 1.12-1.20, I-2 = 51%) per 5 kg of weight gained between young adulthood and study baseline, 1.27 (95% CI 1.17-1.39, I-2 = 71%) per 10 cm increase in waist circumference, 1.21 (95% CI 1.13-1.29, I-2 = 0%) per 0.1-unit increment in waist-to-hip ratio and 1.30 (95% CI 1.19-1.41, I-2 = 0%) per 10-cm increase in hips circumference. The summary RR was 1.15 (95% CI 1.09-1.22, I-2 = 61%) for a 10-cm increase in height. Conclusions: All measures of adiposity were associated with increased risk of endometrial cancer, and in addition increasing height was associated with increased risk.