Chronic statin therapy and the risk of colorectal cancer

Background and Aims Epidemiologic studies on a potential chemopreventive effect of statin therapy hake yielded conflicting results. We sought to clarify whether long-term statin therapy has a chemopreventive effect on the risk of colorectal cancer (CRC) in a large, population-representative cohort. Methods A nested case-control study was conducted among patients >= 50 years of age and with >= 5 years of CRC-free initial follow-up in the General Practice Research Database (GPRD; 1987-2002). Cases consisted of all patients with incident CRC. Up to 10 controls were matched with each case on practice site and both duration and calendar time of follow-up prior to the index date. The primary exposure of interest was >= 5 years of cumulative statin use. Results We identified 4432 incident CRC cases and 44292 controls. The adjusted odds ratio (OR) for >= 5 year; of statin exposure was 1.1 (95% confidence interval (Cl): 0.5-2.2). Chronic NSAID/aspirin use did not modify this primary association (test for interaction, p=0.5). Compared to statin non-users, the adjusted OR for 10 years of statin exposure was 1.3 (95% Cl: 0.6-2.7), and the adjusted OR associated with the highest quartile of cumulative statin dose was 1.2 (95% Cl: 0.9-1.7). There was a non-statistically significant trend towards a possible reduction in CRC risk among users of high daily statin dose. Conclusion Long-term statin therapy at usual doses was not associated with a significantly reduced risk of CRC. A chemopreventive effect at high daily doses cannot be excluded. Copyright (C) 2008 John Wiley & Sons, Ltd.