Aspirin may benefit patients at high risk for colorectal cancer

Patients at high risk for colorectal cancer because of Lynch syndrome, also called hereditary nonpolyposis colon cancer, may benefit from long-term daily aspirin therapy, according to a recent analysis.

Researchers evaluated data from the second Colorectal Adenoma/carcinoma Prevention Programme (CAPP2), a randomized, controlled trial examining aspirin chemoprevention in patients with Lynch syndrome. CAPP2 participants were randomly assigned to receive daily doses of 600 mg of aspirin or aspirin placebo or 30 g of resistant starch or starch placebo for a maximum of four years. The study's primary endpoint was colorectal cancer. Study results were published online Oct. 28 by The Lancet.

Participants were recruited into the study from Jan. 1, 1999 to March 10, 2005. A total of 861 people with Lynch syndrome were assigned to receive aspirin or aspirin placebo. At a mean of 55.7 months of follow-up, 18 of 427 participants in the aspirin group and 30 of 434 in the aspirin placebo group had developed primary colorectal cancer. In an intention-to-treat analysis of time to first colorectal cancer, the hazard ratio in the aspirin group was 0.63 (95% CI, 0.35 to 1.13; P=0.12), and in Poisson regression analysis, which considered more than one primary event, the incidence rate ratio was 0.56 (95% CI, 0.32 to 0.99; P=0.05). Participants who continued the intervention for two years had a hazard ratio of 0.41 (95% CI, 0.19 to 0.86; P=0.02) and an incidence rate ratio of 0.37 (95% CI, 0.18 to 0.78; P=0.008). The groups did not differ in adverse events during the intervention period, although information on adverse events after the intervention was not available.

The authors concluded that aspirin at a dose of 600 mg/d taken for a mean of 25 months reduced incidence of colorectal cancer in patients with Lynch syndrome. They called for additional studies to determine the best dose and duration of aspirin therapy for this indication; CAPP3 intends to examine these questions. An accompanying editorial pointed out that endpoints were not ascertained in a standardized manner and that the aspirin group could have had more postintervention adverse events and therefore more extensive colonoscopy than the nonaspirin group. However, the editorialists wrote, while the study does not allow definitive conclusions, the results “strongly support routine use of aspirin for patients with Lynch syndrome as an adjunct to intensive cancer surveillance.”