Taking aspirin or an omega-3 polyunsaturated fatty acid daily did not reduce the colorectal adenoma detection rate among high-risk patients in a randomized, placebo-controlled trial, though both drugs showed potential chemopreventive effects.
There was no evidence that aspirin, eicosapentaenoic acid (EPA), or the two agents combined had any effect on the adenoma detection rate, reported Mark A. Hull, PhD, of the Institute of Biomedical and Clinical Sciences at the University of Leeds (England), and his coinvestigators.
However, both agents decreased the mean number of adenomas per participants, and showed subtype- and location-specific reductions in adenomas that were consistent with previous studies, according to the investigators.
“Existing data on colorectal cancer risk reduction by aspirin suggest that the decrease in colorectal adenoma recurrence that we report for both agents is likely to translate into a clinically meaningful decrease in long-term colorectal cancer risk,” Dr. Hull and his coauthors said in the report, which appears in the Lancet.
Their randomized, double-blind, multicenter trial, known as the seAFOod Polyp Prevention trial, included participants aged 55-73 years with high-risk adenoma features at screening colonoscopy. A total of 709 participants were enrolled between November 2011 and June 2016.
Adenoma detection rate, the primary endpoint, was 62% overall, and similarly, 63% in the EPA group, 61% in the aspirin group, 61% in the EPA plus aspirin group, and 61% for placebo. There was no evidence that either drug had any effect on this endpoint, according to investigators, who reported risk ratios of 0.98 (95% confidence interval, 0.87-1.12) for EPA and 0.99 (95% CI, 0.87-1.12) for aspirin.
However, aspirin reduced the mean total number of adenomas per participant versus placebo (incidence rate ratio, 0.78; 95% CI, 0.68-0.90), as well as the number of adenomas in the right colon (IRR, 0.73; 95% CI, 0.61-0.88).
While EPA by contrast did not conclusively reduce the mean total number of adenomas per participant, it did reduce the number of adenomas in the left colon, with an IRR of 0.75 (95% CI, 0.60-0.94).
Both aspirin and EPA were generally well tolerated, according to Dr. Hall and his colleagues, though the number of gastrointestinal adverse events was higher in the EPA-alone group, at 146 events, versus 85, 86, and 68 events in the placebo, aspirin, and EPA plus aspirin groups, respectively.
To optimize use of aspirin and EPA for prevention of colorectal adenomas, the approach might need to be tailored to the individual patient, Dr. Hall and his coauthors wrote.
“A key objective of future work will be to apply precision medicine principles to establish which individuals might gain most from chemoprevention with one or both agents, based on baseline colorectal adenoma characteristics alone or together with other mucosal biomarkers,” they added.
Trial funding came from the U.K. Medical Research Council and the National Institute for Health Research. Medicine and placebo were provided without charge by SLA Pharma and Bayer. Dr. Hull provided disclosures related to SLA Pharma, Bayer, and Thetis Pharmaceuticals.
SOURCE: Hull MA et al. Lancet. 2018 Nov 19. doi: 10.1016/S0140-6736(18)31775-6.