Dietary glycemic index, glycemic load, and the risk of endometrial cancer : a case-control study and meta-analysis

Carbohydrates and the dietary glycemic index (GI) influence insulin secretion and insulin-like growth factors, and may exert relevant effects on obesity and diabetes, both of which are important risk factors for endometrial cancer. We studied the association between dietary GI and glycemic load (GL) and endometrial cancer using data from an Italian case-control study. This included 454 women with histologically confirmed endometrial cancer and 908 controls admitted to the same hospitals for acute, non-neoplastic conditions. Multivariate odds ratios were obtained after allowance for major potential confounding factors, including noncarbohydrate energy intake. We updated a meta-analysis on this issue, including a recent US cohort study, which contributed about a quarter of all cases, besides our case-control study. In the case-control study, the odds ratios of endometrial cancer for the highest versus the lowest quintile were 1.03 [95% confidence interval (CI): 0.67-1.58] for GI and 1.01 (95% CI: 0.64-1.61) for GL. No heterogeneity was found across the strata of diabetes and other selected covariates. The summary risk estimate of endometrial cancer for the highest versus the lowest GI level, obtained from the meta-analysis, was 1.09 (95% CI: 0.92-1.29). The corresponding risk estimate for GL was 1.19 (95% CI: 1.06-1.34). The case-control study showed no association between dietary GI and GL and the risk of endometrial cancer overall and in the strata of relevant covariates, whereas the meta-analysis supported an increased risk for high GL, but not GI.