Using aspirin to reduce the risk of colon cancer

From M, spring 2003

University of Minnesota research, part of a seven-year Dartmouth Medical School study, shows that a daily dose of aspirin can be effective in reducing the risk of colon adenomas, the benign tumors that can develop into cancer if left in the bowel.

"This [finding] will be particularly valuable for people who are at increased risk for cancer because they have had colon adenomas (polyps) or because they have previously been treated for colorectal cancer," says Timothy Church, associate professor in the University's School of Public Health and principal investigator for the study in Minnesota.

Some patients in the randomized, double-blind study received aspirin (either 81 mg or 325 mg) while others received a placebo. Interestingly, the group receiving the 81 mg dose of aspirin (the equivalent of what is called a low-dose aspirin) showed a lower incidence of recurring polyps than did those treated with the larger dose of aspirin (the equivalent of a standard adult aspirin.)

Overall, those treated with a daily dose of low-dose aspirin found their risk of polyps reduced 19 percent and their risk of advanced lesions reduced by more than 40 percent.

But a companion study, conducted with patients who have already had colorectal cancer, tested a regular aspirin tablet (325 mg) against a placebo. That dosage showed even larger reductions in the occurrence of adenoma, about a 35 percent reduction.

Although aspirin is generally a safe drug, it can have adverse effects for some individuals. Before people embark on a daily aspirin regimen, they should check with their doctor. Regular screenings, perhaps including colonoscopies, are still important.

Editor's note: In the fall issue of M, we will explore University research into salicylate, found in the bark of willow trees and other plants and first used by the Bayer company in 1899 to make aspirin.