Chemopreventive effect of NSAIDs on colorectal adenomas confirmed

Observational follow-up study and meta-analysis show NSAIDs reduced risk of recurrence.

Data from two studies published in the Journal of the National Cancer Institute confirmed that aspirin and other NSAIDs are effective in the prevention of colorectal adenomas.

The first study was an observational follow-up to the Aspirin/Folate Polyp Prevention study. Results suggested that continued use of NSAIDs extended the chemopreventive effects that aspirin had against colorectal adenomas during the initial treatment period.

“Our study provides further evidence of an inverse association between NSAIDs and colorectal adenomas,” Maria V. Grau, MD, of the department of community and family medicine at Dartmouth Medical School in New Hampshire, told HemOnc Today. “Moreover, our data suggest that long-term, regular use of these drugs does not diminish their chemopreventive potential, but might even enhance it.”

In the double-blind, placebo-controlled, Aspirin/Folate Polyp Prevention study, 1,121 participants were randomly assigned to receive 81 mg per day of aspirin, 325 mg per day of aspirin or placebo for three years.

At the end of study treatment and follow-up colonoscopy, 1,007 participants continued with a follow-up analysis until their next surveillance colonoscopy, which was scheduled three to five years later. Eight hundred fifty participants who underwent a post-treatment colonoscopy within four years following initial study treatment were included in the current analysis.

NSAID use was recorded via periodic questionnaires sent to study participants; NSAID use was classified as sporadic (less than two days per week), moderate (two to three days per week) or frequent (four or more days per week). Primary outcome measures were all adenomas and advanced lesions.

Data indicated a persistent, protective effect on colorectal adenomas with the use of 81 mg aspirin. Frequent NSAID users had a 26.8% risk of any adenoma compared with 39.9% of patients assigned to placebo who later used NSAIDs sporadically (adjusted RR=0.62; 95% CI, 0.39-0.98). Results for 325 mg aspirin were similar, but not statistically significant.

“Because our results imply that the strength of the inverse association between NSAID use and adenoma risk may increase with frequency of use and because more frequent use is also likely to cause more adverse events, further investigation is important to understand ways to maximize the possible benefits of these drugs while minimizing their potential harms,” the researchers wrote.

Meta-analysis confirmed inverse association

The use of aspirin to prevent colorectal adenomas in people with a history of the lesions was further confirmed in the results of a meta-analysis conducted by Bernard et al.

The researchers combined data from four randomized, double blind, placebo-controlled trials that evaluated aspirin as the secondary prevention of colorectal adenomas among 2,698 participants. Aspirin dosage ranged from 81 mg per day to 325 mg per day.

Adenomas were identified in 37% of the 1,156 participants in the placebo group and in 33% of the 1,542 participants assigned to any dose of aspirin.

Advanced lesions were found in 9% of participants assigned to any dose of aspirin compared with 12% of participants in the placebo group.

“Overall, we found a statistically significant 17% decrease in the relative risk of adenoma for aspirin in any dose vs. placebo, which corresponded to a 6.7% absolute risk reduction. We also observed a 28% decrease in the relative risk of advanced lesions,” the researchers wrote. “These benefits need to be considered in the context of all of the health effects of aspirin — positive and negative.”

J Natl Can Inst. 2009;101:267-276.

J Natl Can Inst. 2009;101:256-266.