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Does Aspirin Prevent Development of Colorectal Polyps?

Low-dose aspirin, in conjunction with screening and surveillance, helped to prevent recurrent adenomas.

Researchers have shown that nonsteroidal anti-inflammatory drugs (NSAIDs) induce regression of colorectal polyps in patients with familial polyposis. Now, in 2 randomized double-blind trials, investigators examined whether aspirin prevents the development of polyps in patients without familial polyposis.

In one trial, 635 patients with previously resected colorectal cancer received daily aspirin (325 mg) or placebo. During an average follow-up of 31 months (during which most patients underwent 1 or 2 colonoscopies), aspirin recipients were significantly less likely than placebo recipients to develop 1 or more adenomatous polyps (17% vs. 27%). Due to this finding, the study was stopped early. Similar numbers of adverse events occurred in the 2 groups.

In the second trial, 1121 patients who had recently undergone removal of at least 1 adenomatous polyp received daily aspirin (81 or 325 mg) or placebo. During an average follow-up of 33 months, at least 1 adenoma was diagnosed in 38%, 45%, and 47% of patients in the 81-mg-aspirin, 325-mg-aspirin, and placebo groups, respectively. Only the difference between the 81-mg-aspirin group and the placebo group was significant. There were nonsignificant trends toward more adverse events among aspirin recipients than among placebo recipients.

Comment: The authors and an editorialist conclude that aspirin reduces risk for recurrent adenomas in patients with previously resected cancers or adenomas. Yet, they acknowledge that aspirin's effect was moderate in these studies, and they find it puzzling that 81 mg, but not 325 mg, was effective in the second study. Moreover, low-dose aspirin is not entirely risk free. In the final analysis, the editorialist concludes that aspirin "cannot yet be recommended [for preventing colorectal cancer] and is not a substitute for screening and surveillance."

— Allan S. Brett, MD

Published in Journal Watch General Medicine March 21, 2003

Citation(s):

Sandler RS et al. A randomized trial of aspirin to prevent colorectal adenomas in patients with previous colorectal cancer. N Engl J Med 2003 Mar 6; 348:883-90.

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• Medline abstract (Free)

Baron JA et al. A randomized trial of aspirin to prevent colorectal adenomas. N Engl J Med 2003 Mar 6; 348:891-9.

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• Medline abstract (Free)

Imperiale TF. Aspirin and the prevention of colorectal cancer. N Engl J Med 2003 Mar 6; 348:879-80.

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• Medline abstract (Free)