Statin use and mortality in patients with colorectal cancer: A systematic review and meta-analysis of observational studies.

Abstract

686 Background: Preclinical evidence suggests that statins have anti-neoplastic properties by inhibiting cell proliferation, and inducing apoptosis. Statins may be associated with reduced risk of colorectal cancer (CRC), but their effect on CRC related mortality is unclear. We performed a meta-analysis of published observational studies evaluating statin use in patients with CRC and its association with overall and CRC-specific mortality. Methods: Through a systematic search upto August 2014, we identified 7 observational studies (64,773 patients with CRC;19.5% statin users) reporting the association between statin use and mortality in patients with CRC. Summary hazard ratio (HR) with 95% confidence intervals (CI) was estimated using the random effects model, and heterogeneity was measured using the inconsistency index (I2). Results: On meta-analysis, statin use was associated with a 26% reduction in all-cause mortality in CRC patients as compared to non-use (6 studies; adjusted HR, 0.74; 95% CI, 0.67-0.83) with minimal heterogeneity (I2=18%), after adjusting for age, sex and CRC stage. Only one study adjusted for concomitant metformin use. Five studies evaluated CRC-specific mortality; on meta-analysis, use of statins (vs non-use) was also associated with decreased CRC-specific mortality (adjusted HR, 0.74; 95% CI, 0.70-0.83; minimal heterogeneity, I2=17%). On limiting analysis to statin use after diagnosis of CRC, use of statins remained significantly associated with reduced CRC-specific mortality (3 studies; adjusted HR, 0.70; 95% CI, 0.60-0.81), but not overall mortality (4 studies; adjusted HR, 0.82; 95% CI, 0.64-1.05). On restricting analysis to studies, which adjusted for concomitant use of aspirin/NSAID, the inverse association between statin use and overall- (5 studies; adjusted HR, 0.74; 95% CI, 0.66-0.84) and CRC-specific mortality (4 studies; adjusted HR, 0.76; 95% CI, 0.69-0.84) remained significant. Conclusions: Based on this meta-analysis, statin use in patients with CRC may be associated with reduced all-cause and CRC-specific mortality. This observation merits prospective investigation of statins’ effect on outcome in CRC patients.