Carbohydrate quantity and quality affect the risk of endometrial cancer: A systematic review and dose-response meta-analysis

Background: Data on the association of dietary intake of total carbohydrates as well as dietary glycemic index (GI) and glycemic load (GL) with risk of endometrial cancer are contradictory. Therefore, we conducted a systematic review and dose-response meta-analysis of observational studies to summarize available findings in this field. Methods: The online databases were searched for relevant publications to May 2018 using relevant keywords. Results: Overall, eight prospective cohort and five case-control studies with a total sample size of 734,765 individuals, aged �18 years, and 8466 cases of endometrial cancer were included. Although the overall association between dietary intake of total carbohydrates and risk of endometrial cancer was non-significant, we found a significant positive association in some subgroups of cohort studies including those with �10 years' duration of follow-up (combined effect size: 1.29, 95 CI: 1.09�1.53, P = 0.003) and studies with sample size of �50,000 participants (combined effect size: 1.24, 95 CI: 1.08�1.43, P = 0.002). In addition, a non-linear dose-response relationship was found in this regard after considering the estimates from cohort studies (Pnonlinearity = 0.002). Combining effect sizes from case-control studies showed a significant positive association between dietary GI and risk of endometrial cancer; such that a-10 unit increase in GI was associated with a 4 greater risk of endometrial cancer (combined effect size: 1.04, 95 CI: 1.02�1.05, P < 0.001). There was also a significant positive association between dietary GL and risk of endometrial cancer in some subgroups of cohort studies and also in non-linear dose-response analysis. Conclusions: Although the overall associations of dietary total carbohydrate intake, GI, and GL with risk of endometrial cancer were not significant, there were significant positive associations in some subgroups of the included studies, particularly those with high quality. There was also a dose-response association between dietary total carbohydrate intake, GI and GL, and risk of endometrial cancer. © 2019 Elsevier Ltd and European Society for Clinical Nutrition and Metabolis