Nonsteroidal anti-inflammatory drugs and cancer prevention

Nonsteroidal anti-inflammatory drugs (NSAIDs), including aspirin, appear to have clinically significant anticarcinogenic effects in the gastrointestin al tract. Epidemiological data indicate that use of these drugs is inversel y associated with the risk of sporadic colorectal cancer, and clinical tria ls among patients with familial polyposis coli show that NSAIDs can lead to the regression of large bowel adenomas. Animal studies have reported a sim ilar efficacy of NSAIDs against experimental carcinogenesis. A consistent p attern in this research is that continued long-term use of NSAIDs is requir ed for an anticancer effect-up to 15 or 20 years before a reduced risk of c olorectal cancer appears. Epidemiological data also suggest possible protec tive effects in the stomach and esophagus. The mechanisms underlying any ch emopreventive effect of NSAIDs are not clear. Inhibition of cyclooxygenase is one possibility, but pathways independent of cyclooxygenase and prostagl andins are also possible.