ASPIRIN AND NONSTEROIDAL ANTIINFLAMMATORY DRUG-USE AND THE RISK OF SUBSEQUENT COLORECTAL-CANCER

Objective: To test the hypothesis that the regular use of aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) is negatively asso ciated with the risk of subsequent colorectal cancer. Design: Case-con trol study with four age- and sex-matched control subjects for each in cident colorectal cancer case. Population and Setting: Patient populat ion of a large municipal teaching hospital in Atlanta, Ga. Main Outcom e Measure: Odds of colorectal cancer as a function of aspirin, nonaspi rin NSAIDs, and acetaminophen dispensed to the study population in the 4 years prior to incident colorectal cancer diagnosis. Main Results: The risk of colorectal cancer estimated by odds ratios decreased with inceasing days of exposure to aspirin linearly in a dose-dependent fas hion (likelihood ratio statistic: for cumulative days, P<.001; for cum ulative dose, P<.001). The coefficient for days of exposure to aspirin was highly significant even when modeled as a continuous variable (P= .001). There appeared to be a threshold above which nonaspirin NSAIDs afforded protection (likelihood ratio statistic: for cumulative days, P=.021; for cumulative dose,P=.019). Acetaminophen conferred no risk r eduction. Conclusion: The results of previous experimental animal mode ls, interventional case studies, and some but not all epidemiological investigations and the present data point toward a causal relationship between NSAID use and the prevention of cancer of the large bowel and rectum. Because of the potential gastrointestinal and renal side effe cts of NSAID use, particularly in the elderly, chemoprevention trials are now needed to allow risk-benefit analysis in populations at high r isk for colorectal cancer.