Association Between Mediterranean Diet Adherence And Colorectal Cancer

Objectives:Mounting epidemiologic studies have investigated the potential inverse association between Mediterranean diet(MD)adherence and colorectal cancer(CRC)incidence and mortality.However,the results are inconsistent.This meta-analysis aimed to investigate the association between Mediterranean diet and CRC incidence and mortality.Methods:PubMed,Embase and Web of Science were searched to identify eligible studies through September 2019.A random-effects model was used to estimate summary relative risks(RRs)and 95%confidence intervals(CIs).We performed the Q test and I~2 statistics to test and quantify the heterogeneity among the studies.In meta-regression analyses,we used a random-effects model with the Knapp-Hartung method.Begg’s test and Egger’s test were conducted to detect potential publication bias.The results were examined through analyses stratified by geographic area,MD score system,sex,cancer site,etc.Results:This meta-analysis included 13 prospective cohort studies,of which 9reported CRC incidence and 5 reported CRC mortality.The summary RR of CRC incidence was 0.90(95%CI:0.84,0.96)for highest compared to lowest MD adherence and 0.96(95%CI:0.94,0.99)per 2-score increase in MD adherence.The summary RR was 0.82 for rectal cancer(95%CI:0.71,0.95),0.94 for proximal colon cancer(95%CI:0.87,1.02)and 0.91 for distal colon cancer(95%CI:0.79,1.04).Neither the summary hazard ratio(HR)of overall mortality for highest vs.lowest pre-and post-diagnosis MD adherence,nor the summary HR of CRC-specific mortality for pre-diagnosis MD adherence achieved a value with statistical significance.Conclusions:Our meta-analysis supports the inverse association of MD adherence with CRC incidence,but not with overall mortality or CRC-specific mortality among those diagnosed with CRC.