CHICAGO – The authors say that aspirin could prove to be an effective strategy in preventing early-onset colorectal cancer cases.
“What we have here is a 15% reduction for all adenomas and 33% for those with advanced histology, which to us is quite substantial. We have not seen that much [33%] in previous studies so I would think it definitely needs more study,” said Cassandra D. Fritz, MD, MPHS, a gastroenterologist with Washington University, St. Louis, in an oral presentation given at the annual Digestive Disease Week®.
Dr. Cassandra D. Fritz
“This finding is important given the alarming rise in the incidence and mortality of early-onset colorectal cancer (age < 50 years), and our limited understanding of the underlying drivers to direct prevention efforts,” Dr. Fritz said. Early-onset colorectal cancer cases have doubled since 1995, she said.
The study confirms evidence from 30 years of research that suggests regular aspirin use reduces cancer risk. In patients with Lynch syndrome, the CAPP2 study showed that aspirin has a protective effect against colorectal cancer at 20 years follow-up.
While emerging data have suggested that aspirin use may reduce later-onset colorectal cancer, it was not known if regular aspirin and NSAID use are associated with diminished risk of early-onset conventional adenomas, and especially the high-risk adenomas conferring greater malignant potential known to be the major precursor of early-onset colorectal cancer. An unpublished analysis of molecular markers by the study’s senior author, Yin Cao, ScD, MPH, also of Washington University, found that at least 57% of early-onset colorectal cancers developed from the conventional adenoma-carcinoma pathway.
Dr. Yin Cao
The objective of the new study was to assess the association between regular aspirin or NSAID use at least twice weekly, with the risk of developing early-onset adenoma. The analysis is based on an evaluation of data from the Nurses’ Health Study II of 32,058 women who had at least one colonoscopy before age 50 (1991-2015). High-risk adenomas included those that were at least 1 cm with tubulovillous/villous histology or high-grade dysplasia, or the presence of at least three adenomas.
There were 1,247 early-onset adenomas, among which 290 were considered high risk. The risk of adenomas among patients who took aspirin or NSAIDs regularly for cardiovascular protection or for inflammatory conditions, was lower than in those who did not take aspirin and/or NSAIDs regularly. While the association was similar for high-risk vs. low-risk adenomas, the benefit was more pronounced for adenomas of tubulovillous/villous histology or with high-grade dysplasia (odds ratio, 0.67; 95% confidence interval, 0.51-0.89), a 33% reduction, compared with tubular adenomas (OR, 0.90; 95% CI, 0.79-1.0; P for heterogeneity = .02).
With later-onset adenomas, risk reduction was confined primarily to large (OR, 0.76; 95% CI, 0.62-0.93) or multiple adenomas (OR, 0.57; 95% CI, 0.40-0.83), but not adenomas of advanced histology (OR, 0.92; 95% CI, 0.73-1.17).
“With colorectal cancer rates increasing, we still don’t have any preventative strategies beyond screening. With this 15% reduction with aspirin/NSAIDS in early-onset adenoma – and particularly for the quite substantial 33% benefit in advanced adenoma with advanced histology, we need to think about a precision-based chemoprevention strategy for early-onset precursors of colorectal cancer,” Dr. Cao said.
The U.S. Preventive Services Task Force issued a new recommendation in 2021 stating that colorectal cancer screening for people with average risk should start 5 years sooner at age 45. “As we know,” Dr. Yin said, “many younger adults are not screened. That’s why we’re looking into potential early-onset colorectal cancer chemopreventative agents.”
DDW is sponsored by the American Association for the Study of Liver Diseases, the American Gastroenterological Association, the American Society for Gastrointestinal Endoscopy, and the Society for Surgery of the Alimentary Tract.
Dr. Fritz had no disclosures and Dr. Cao listed consulting for Geneoscopy.