Statins and the risk of colorectal cancer: A meta-analysis of 18 studies involving more than 1.5 million patients

Purpose Statins have been suggested to prevent colorectal cancer. Several epidemiologic studies have evaluated this association, whereas randomized controlled trials (RCTs) on cardiovascular outcomes provide relevant data as a secondary end point. Our aim was to examine the strength of this association through a detailed meta-analysis of the studies published on the subject in peer-reviewed literature. Methods A comprehensive search for studies published up to December 2006 was performed, reviews of each study were conducted, and data were abstracted. Before meta-analysis, the studies were evaluated for publication bias and heterogeneity. Pooled relative risk (RR) estimates with 95% Cls were calculated using the fixed-and random-effects models. Results Eighteen studies involving more than 1.5 million participants contributed to the analysis. They were grouped on the basis of study design, and separate meta-analyses were conducted. There was no evidence of an association between statin use and risk of colorectal cancer either among RCTs (RR = 0.95; 95% Cl, 0.80 to 1.13; n = 6) or among cohort studies (RR = 0.96; 95% Cl, 0.84 to 1.11; n = 3). However, statin use was associated with a modest reduction in the risk of colorectal cancer among case-control studies (RR = 0.91; 95% Cl, 0.87 to 0.96; n = 9). Low evidence of publication bias or heterogeneity was found. Conclusion Our meta-analysis results do not support the hypothesis that statins strongly reduce the risk of colorectal cancer, when taken for management of hypercholesterolemia. However, we cannot rule out a modest reduction in risk or an effect associated with higher doses of statins.