Background and aims: Epidemiologic studies on a potential chemopreventive effect of statin therapy have 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 > or =50 years of age and with > or =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 > or =5 years of cumulative statin use.
Results: We identified 4432 incident CRC cases and 44 292 controls. The adjusted odds ratio (OR) for > or =5 years of statin exposure was 1.1 (95% confidence interval (CI): 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% CI: 0.6-2.7), and the adjusted OR associated with the highest quartile of cumulative statin dose was 1.2 (95% CI: 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.