Experimental and observational studies suggest that regular aspirin use may decrease the risk of colorectal adenomas.
In this study, researchers from the United States conducted a randomized, double-blind trial to determine the effect of aspirin on the incidence of colorectal adenomas.
The research team randomly assigned 635 patients with previous colorectal cancer to receive either 325 mg of aspirin per day or placebo.
|1 or more adenomas were found in 17% of patients in the aspirin group and in 27% in the placebo group.|
|New England Journal of Medicine|
They determined the proportion of patients with adenomas, the number of recurrent adenomas, and the time to the development of adenoma between randomization and subsequent colonoscopic examinations.
The team adjusted relative risks for age, sex, cancer stage, the number of colonoscopic examinations, and the time to a first colonoscopy.
The study was terminated early by an independent data and safety monitoring board when statistically significant results were reported during a planned interim analysis.
The researchers determined that a total of 517 patients had at least 1 colonoscopic examination a median of 12.8 months after randomization.
The team found 1 or more adenomas in 17% of patients in the aspirin group and in 27% in the placebo group.
Furthermore, the mean number of adenomas was lower in the aspirin group than the placebo group (0.30 versus 0.49, respectively).
The team also found that the adjusted relative risk of any recurrent adenoma in the aspirin group, compared with the placebo group, was 0.65.
Additionally, the team found that the time to the detection of a first adenoma was longer in the aspirin group than in the placebo group.
Dr Robert Sandler’s team concluded, “Daily use of aspirin is associated with a significant reduction in the incidence of colorectal adenomas in patients with previous colorectal cancer”.
In a separate but related study in the same publication, researchers performed a randomized, double-blind trial of aspirin as a chemopreventive agent against colorectal adenomas.
They assigned 1121 patients with a recent history of histologically documented adenomas to receive placebo, 81 mg of aspirin, or 325 mg of aspirin daily.
According to the protocol, follow-up colonoscopy was to be performed approximately 3 years after the qualifying endoscopy.
The team compared the groups with respect to the risk of 1 or more neoplasms (adenomas or colorectal cancer) at least 1 year after randomization.
The researchers found that reported adherence to study medications, and avoidance of nonsteroidal anti-inflammatory drugs were both excellent.
They performed follow-up colonoscopy at least 1 year after randomization in 97% of patients.
The team found that the incidence of 1 or more adenomas was 47% in the placebo group, 38% in the 81-mg aspirin group, and 45% in the 325-mg aspirin group.
Unadjusted relative risks of any adenoma were 0.81 in the 81-mg group and 0.96 in the 325-mg group.
For advanced neoplasms, the team found that the respective relative risks were 0.59 and 0.83.
Dr John Baron’s team concluded, “Low-dose aspirin has a moderate chemopreventive effect on adenomas in the large bowel”.