Background & aims: Aspirin and nonsteroidal anti-inflammatory drugs have been reported to protect against the development of colorectal cancer. Because adenomas are precursors to most colorectal cancers, the aim of this study was to examine the relationship of these medications to the risk for colorectal adenomas in a colonoscopy-based case-control study.
Methods: Study participants were drawn from patients who underwent colonoscopy at the University of North Carolina Hospitals. Medication use was assessed by telephone using a comprehensive list of prescription and nonprescription drugs as well as questions about dietary and lifestyle factors that might be relevant for adenoma development.
Results: There were 210 patients with adenomas and 169 adenoma-free controls. After adjusting for potential confounders, regular users were half as likely to currently have adenomas compared with nonusers (adjusted odds ratio, 0.56; 95% confidence interval, 0.34-0.92). Regular users who stopped medication at least 1 year before colonoscopy were still protected (adjusted odds ratio, 0.59; 95% confidence interval, 0.21-1.67), although small numbers make this conclusion tentative. The protective effects of aspirin and the nonaspirin nonsteroidal anti-inflammatory drugs were similar.
Conclusions: The results suggest that aspirin and nonsteroidal anti-inflammatory drugs cause early disruption of the adenoma-carcinoma sequence. The challenge for the future will be to learn more about dose, duration, and mechanism of action.