Background and aims: Several studies suggest that statins prevent some cancers, with one study finding a 47% reduction in colorectal cancer risk after >or=5 years of regular use.

Methods: A nested case-control study was conducted within 454 general practices in the United Kingdom using the QRESEARCH database. Cases with colorectal cancer were diagnosed between 1995 and 2005. The effects of statins, nonsteroidal anti-inflammatory drugs, cyclooxygenase-2 inhibitors, and aspirin on colorectal cancer were estimated with conditional logistic regression adjusted for morbidity, smoking status, body mass index, and socioeconomic status.

Results: We analyzed 5686 cases and 24,982 matched controls with >or=4 years of records. The adjusted odds ratio for colorectal cancer associated with any statin prescription was 0.93 (95% confidence interval: 0.83-1.04), with no trend in duration of use or number of prescriptions. For any nonsteroidal anti-inflammatory drug prescription the adjusted odds ratio was 0.94 (95% confidence interval: 0.88-1.00), with a significant decrease in risk with increasing number of prescriptions and an adjusted odds ratio of 0.76 (0.60-0.95) for >or=25 prescriptions. Prolonged use of cyclooxygenase-2 inhibitors was minimal, but for those receiving >or=25 prescriptions the adjusted odds ratio was 0.34 (0.14-0.85). Results were similar in the subset of participants with >or=8 years of records; the adjusted odds ratio for >or=61 months of statin prescriptions was 1.00 (0.67-1.48).

Conclusions: In this large population-based case-control study prolonged use of nonsteroidal anti-inflammatory drug and cyclooxygenase-2 inhibitor was associated with a reduced colorectal cancer risk, but prolonged statin use was not.