AIM:To investigate the association between statin use and colorectal cancer risk,we conducted an updated meta-analysis of published studies.METHODS:We performed a comprehensive search for studies published up to July 2013.Eligible studies for this meta-analysis were either randomized controlled trials(RCTs)or observational studies(casecontrol or cohort)evaluating any exposure to statins and the risk of colorectal cancer.Two reviewers selected studies based on predefined inclusion criteria,and abstracted the data.Pooled relative risk(RR)estimates with their 95%CI were calculated using fixedand random-effects models.Then,we assessed the potential presence of publication bias and betweenstudies heterogeneity.To evaluate the results,we also performed a“leave-one-out”sensitivity analysis.RESULTS:A total of 40 studies,involving more than eight million subjects,contributed to the analysis.They were grouped on the basis of study design and,consequently,three separate meta-analyses were conducted.A similar modest reduction in the risk of colorectal cancer with statin use was observed,which was not statistically significant among RCTs(RR=0.89,95%CI:0.74-1.07;n=8),but reached statistical significance among cohort studies(RR=0.91,95%CI:0.83-1.00;n=13)and case-control studies(RR=0.92,95%CI:0.87-0.98;n=19).While we did not find significant evidence of selective outcome reporting or publication bias,substantial heterogeneity was detected,mainly among the observational studies.The sensitivity analysis confirmed the stability of our results.CONCLUSION:A modest reduction in risk of colorectal cancer among statin users cannot be disproved.Further targeted research is warranted.2014 Baishideng Publishing Group Co.,Limited.All rights To investigate the association between statin use and colorectal cancer risk, we conducted an updated meta-analysis of published studies. METHODS: We performed a comprehensive search for studies published up to July 2013. Eligible studies for this meta-analysis were either randomized controlled trials (RCTs) or observational studies (casecontrol or cohort) serving any exposure to statins and the risk of colorectal cancer. Two reviewers selected studies based on predefined inclusion criteria, and abstracted the data. Pooled relative risk (RR) estimates with their 95 % CI were calculated using fixed and random-effects models. Chen, we assessed the potential presence of publication bias and between heterozygosity.To evaluate the results, we also performed a “leave-one-out” sensitivity analysis .RESULTS: A total of 40 studies, involving more than eight million subjects, contributed to the analysis. The were were grouped on the basis of study design and, of, three separate meta-analyzes were condu cted. A similar modest reduction in the risk of colorectal cancer with statin use was observed, which was not statistically significant among RCTs (RR = 0.89, 95% CI: 0.74-1.07; n = 8), but reached statistical significance among cohort studies (RR = 0.91, 95% CI: 0.83-1.00; n = 13) and case-control studies (RR = 0.92, 95% CI: 0.87-0.98; n = 19) .While we did not find significant evidence of selective outcome reporting or publication bias, substantial heterogeneity was detected, mainly among the observational studies. sensitivity analysis confirmed the stability of our results. CONCLUSION: A modest reduction in risk of colorectal cancer among statin users can not be disproved. Future focused research is warranted. 2014 Baishideng Publishing Group Co., Limited.All rights