Most epidemiological studies (1 -7 ) support a protective role of aspirin and nonsteroidal antiinflammatory drugs (NSAIDs) against colorectal cancer. People who (by their report) take aspirin regularly have about a 50% decrease in the incidence (3 ,4 ) and mortality (1 ,2 ) from colorectal cancer compared to those who reported no aspirin use. In addition, hospital-based case control studies suggest a protective effect of aspirin use on the development of large-bowel adenomas (5 -7 ). On the other hand, the Physician’s Health Study failed to detect any protective effect for aspirin against the subsequent development of colorectal cancer over 12 years of follow up, although this may be due to the short period of follow up (8 ,9 ).