Statin use and survival in colorectal cancer: Results from a population-based cohort study and an updated systematic review and meta-analysis

•Statin use was associated with a generally weak improvement in survival.•The reduction in cancer-specific mortality was particularly inconsistent.•This raises questions about the potential utility of statins as adjuvant agents.•However, variation in study design limits interpretation of these pooled analyses.•Further robust observational studies are required.

BackgroundThe aim of this study was to investigate the association between statin use and survival in a population-based colorectal cancer (CRC) cohort and perform an updated meta-analysis to quantify the magnitude of any association.MethodsA cohort of 8391 patients with newly diagnosed Dukes' A-C CRC (2009-2012) was identified from the Scottish Cancer Registry. This cohort was linked to the Prescribing Information System and the National Records of Scotland Death Records (until January 2015) to identify 1064 colorectal cancer-specific deaths. Adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for cancer-specific mortality by statin use were calculated using time dependent Cox regression models. The systematic review included relevant studies published before January 2016. Meta-analysis techniques were used to derive combined HRs for associations between statin use and cancer-specific and overall mortality.ResultsIn the Scottish cohort, statin use before diagnosis (HR = 0.84, 95% CI 0.75-0.94), but not after (HR = 0.90, 95% CI 0.77-1.05), was associated with significantly improved cancer-specific mortality. The systematic review identified 15 relevant studies. In the meta-analysis, there was consistent (I2 = 0%,heterogeneity P = 0.57) evidence of a reduction in cancer-specific mortality with statin use before diagnosis in 6 studies (n = 86,622, pooled HR = 0.82, 95% CI 0.79-0.86) but this association was less apparent and more heterogeneous (I2 = 67%,heterogeneity P = 0.03) with statin use after diagnosis in 4 studies (n = 19,152, pooled HR = 0.84, 95% CI 0.68-1.04).ConclusionIn a Scottish CRC cohort and updated meta-analysis there was some evidence that statin use was associated with improved survival. However, these associations were weak in magnitude and, particularly for post-diagnosis use, varied markedly between studies.