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Am Fam Physician. 2004;69(3):739

Daily intake of aspirin has been demonstrated to decrease the risk of colorectal cancer in multiple cohort and case-control studies, although the benefit varies slightly among the studies. Considering the potential toxicity of aspirin, further information about which subgroups would benefit most from its regular use would be helpful. Benamouzig and associates conducted a prospective, randomized, double-blind, placebo-controlled, multicenter trial comparing the effects of a soluble aspirin preparation with placebo on colorectal polyp recurrence.

Patients who had adenomatous polyps diagnosed and removed by colonoscopy were eligible to participate. A total of 272 patients were randomized to receive lysine acetylsalicy-late (160 mg or 300 mg daily) or placebo. The primary end point was the detection of at least one new adenoma at follow-up colonoscopy after one year.

Of the 272 randomized patients, 238 (87.5 percent) underwent colonoscopy one year after enrollment. In these patients, at least one adenoma was found in 38 of the 126 patients (30 percent) in the aspirin group and in 46 of the 112 patients (41 percent) in the placebo group. The recurrence rate of hyperplastic polyps was 11 percent of patients in the aspirin group and 23 percent of patients in the placebo group. The relative risk of polyp recurrence was higher in patients receiving low-dose aspirin therapy than in patients receiving high-dose aspirin therapy.

The authors conclude that regular aspirin use decreases the risk of colorectal adenoma in high-risk patients. The optimal dosage of aspirin required to obtain this benefit and decrease adverse drug effects remains unclear. Although previous studies have noted that long-term aspirin use is required to decrease colorectal cancer occurrence, this study may demonstrate that short-term aspirin use effectively prevents adenoma recurrence in a high-risk subgroup.

In an editorial in the same issue, Dubois points out that aspirin, like other nonsteroidal anti-inflammatory drugs, reduces polyp numbers in patients with familial polyposis. Recent studies demonstrate that aspirin intake seems to decrease adenoma recurrence in patients with a history of adenomas.Whether this therapy actually will decrease colorectal cancer incidence is uncertain. Dubois concludes that physicians can tell patients who are taking daily aspirin for other reasons that they may receive the additional benefit of reduced polyp recurrence.

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