title: Statins and the risk of colorectal cancer: an updated systematic review and meta-analysis of 40 studies.
abstract: OBJECTIVE
  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 (case-control 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 fixed- and random-effects models. Then, we assessed the potential presence of publication bias and between-studies 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.
  
  
  CONCLUSIONS
  A modest reduction in risk of colorectal cancer among statin users cannot be disproved. Further targeted research is warranted.
authors.affiliation: Theodore Lytras, Department of Occupational and Industrial Hygiene, National School of Public Health, 11521 Athens, Greece.
authors.forename: Theodore
authors.initials: T
authors.lastname: Lytras
authors.affiliation: Theodore Lytras, Department of Occupational and Industrial Hygiene, National School of Public Health, 11521 Athens, Greece.
authors.forename: Georgios
authors.initials: G
authors.lastname: Nikolopoulos
authors.affiliation: Theodore Lytras, Department of Occupational and Industrial Hygiene, National School of Public Health, 11521 Athens, Greece.
authors.forename: Stefanos
authors.initials: S
authors.lastname: Bonovas
mesh_terms: D015179:Colorectal Neoplasms / Q000188:drug therapy*; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000627:therapeutic use*; D064887:Observational Studies as Topic; D016032:Randomized Controlled Trials as Topic; D015203:Reproducibility of Results; D012307:Risk Factors; D012680:Sensitivity and Specificity
chemical_list: D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors
keywords: 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors; Cancer chemoprevention; Colorectal cancer; Meta-analysis; Statins; Systematic review