Circulating adiponectin, leptin and adiponectin-leptin ratio and endometrial cancer risk: Evidence from a meta-analysis of epidemiologic studies.

We performed this meta-analysis of epidemiologic studies to investigate the associations between circulating adiponectin, leptin and adiponectin-leptin (A/L) ratio and endometrial cancer risk. Relevant manuscripts were identified by searching PubMed and ISI Web of Science databases as well as by manual searching the references cited in retrieved manuscripts. Random-effects models were used to estimate summary odds ratio (SOR) and 95% confidence intervals (CIs) for aforementioned associations. Fourteen manuscripts with 13 studies (five nested case-control and eight case-control studies) cumulatively involving a total of 1,963 endometrial cancer cases and 3,503 noncases were included in the analyses. Overall, comparing persons with circulating concentrations of adiponectin, leptin and A/L ratio in the top tertile with persons with concentrations of these biomarkers in the bottom tertile yielded SORs of 0.47 (95% CI: 0.34-0.65; I(2)  = 63.7%; n = 13), 2.19 (95% CI: 1.44-3.31; I(2)  = 64.2%; n = 7),and 0.45 (95% CI: 0.24-0.86; I(2)  = 90.1%; n = 5), respectively. Notably, there was an 18% reduction in risk for per each 5 μg/mL increment in circulating adiponectin concentrations (SOR = 0.82; 95% CI: 0.74-0.90; I(2)  = 49%; n = 8). Stratifying by study characteristics and whether these studies considered or adjusted for potential confounders, the findings were robust in the analyses of circulating adiponectin and leptin. No evidence of publication bias was detected. In conclusion, the findings from this meta-analysis suggest that increased circulating adiponectin and A/L ratio or decreased leptin concentrations were associated with reduced risk of endometrial cancer. Further prospective designed studies are warranted to confirm our findings.