The Association Between Overweight,Obesity And Renal Cancer: A Meta-analysis

Objective: Renal cancer is a common urological malignancy,and the incidence has been increasing year by year.Up to now,the pathogenesis of renal cancer is not clear.Some studies suggested that overweight and obesity might be one of the risk factors for renal cancer.However,the results of many epidemiological studies were inconsistent.Therefore,in this study,a meta-analysis was used to analyze the relationship between overweight,obesity and renal cancer.Methods: Database of PubMed,EMbase,Cochrane Library,CBM,CNKI,VIP and Wan Fang were used to search for cohort studies which regarded to the relationship between overweight,obesity and renal cancer up to September 2017.The reference lists of the included articles were checked.The process of study selection,data extraction and quality assessment were conducted by two independent researchers.Statistical analysis was performed by using STATA 12.0 software.The relative risk(RR)and the corresponding 95% confidence interval(CI)were used to measure the association between overweight,obesity and renal cancer.Subgroup-analyses were conducted to explore the source of heterogeneity and assess the effects of various study characteristics on the pooled RR.In addition,we conducted a sensitivity analysis to confirm the stability of the overall results.Finally,the funnel plot and Egger's test were performed to evaluate the potential publication bias.Results: 17 studies were included in our meta-analysis.The study had 17266402 objects with 17758 being the renal cancer cases.According to NOS,17 studies were of high quality since the score was 6 to 9.Meta analysis was carried out through STATA 12.0 software.The results showed that people who were overweight were 1.40 times more likely to develop renal cancer than those with normal weight(RR=1.40,95%CI 1.26-1.55,P<0.05);We found that people who were obesity were 1.74 times more likely to develop renal cancer than those with normal weight(RR=1.74,95%CI 1.59-1.90,P<0.05).Subgroup analysis results showed that,regardless of the gender,the objects from Europe,America or Asia,and the body index was measured or self-reported,overweight and obesity could increase the risk of renal cancer.Sensitivity analysis demonstrated that the positive association between overweight,obesity and renal cancer risk was not modified after excluding each study,which suggested the result was stable.Funnel plot did not show any substantial asymmetry.We detected no publication bias based on Egger's regression test(P>0.05).Conclusion: Our meta-analysis shows that overweight,obesity probably can increase the risk of renal cancer,especially for obesity.It is suggested that more large-sample and multi-center studies should be carried out in the future.Besides,the effect of abdominal obesity should be considered.The mechanism of overweight and obesity to increase the risk of renal cancer is not clear yet,which needs further foundation and clinical research.