Low-Dose Aspirin and Colorectal Cancer Risk Reduction in IBD

April 21, 2026

Issue 08

Clinical Question

What role does low-dose aspirin have in preventing colorectal cancer in IBD?

Editor’s Bottom Line

These observational data associate long-term use of ASA with significant reductions in the risk of colorectal cancer in patients with IBD. Prospective trials should be considered.

Reference

Huang Y-J, Lin J-A, Chen W-M, Shia B-C, Wu S-Y. Low-dose aspirin and the prevention of colorectal cancer in inflammatory bowel disease: a nationwide cohort study. Inflamm Bowel Dis. Epub ahead of print Jan 9, 2026; https://doi.org/10.1093/ibd/izaf304

Synopsis

This was a nationwide propensity score-matched cohort study using Taiwan’s National Health Insurance Research Database (NHIRD) and linked Cancer Registry meant to evaluate the association between long-term aspirin use and colorectal cancer (CRC) incidence and all-cause mortality in patients with IBD. The initial dataset included 199,082 adults 20 years or older diagnosed with IBD between 2008 and 2019, with follow-up through December 31, 2022. Long-term aspirin use was defined as cumulative exposure of ≥28 defined daily doses (cDDDs) per year, consistent with established pharmacoepidemiologic thresholds for sustained use. After 1:1 nearest-neighbor propensity score matching based on age, sex, income, urbanization, IBD duration, Charlson Comorbidity Index score, comorbidities, lifestyle factors and concurrent medication use (including mesalamine, biologics, immunomodulators and statins), the analytic cohort comprised 2,743 aspirin users (prescribed the drug primarily for cardiovascular disease prevention) and 2,743 non-users.

Of these 5,486 matched patients, 77% had ulcerative colitis, 23% had Crohn’s disease and the mean age was approximately 60 years in both groups. The primary endpoint was first histologically confirmed diagnosis of CRC, identified through the Taiwan Cancer Registry, while all-cause mortality was the secondary endpoint. Aspirin exposure was further stratified by cumulative cDDD (less than vs. more than the median) and average daily intensity (<1 defined daily dose per day vs. ≥1DDD/day, with 1 DDD equivalent to approximately 100 mg/day). In the fully adjusted analysis, aspirin use was associated with a significantly lower risk of CRC compared to non-use (adjusted Hazard Ratio [aHR]: 0.42; 95% Confidence Interval [CI], 0.31–0.57; p <0.0001). The incidence of CRC was 29.53 per 10,000 person-years among aspirin users, compared to 69.28 per 10,000 person-years among non-users (incidence rate ratio [IRR]: 0.43; 95% CI, 0.32–0.57). Aspirin use was also associated with reduced all-cause mortality (aHR: 0.66; 95% CI, 0.58–0.74), with consistent findings across all adjustment models. The authors found a clear dose-response relationship for cumulative aspirin exposure: users with cDDD at or below the median had an aHR of 0.56 (95% CI, 0.39–0.80) and those with cDDD above the median had an aHR of 0.31 (95% CI 0.21–0.47; p for trend <0.001). Assessment of daily intensity revealed a nonlinear association, namely showing patients receiving <1 DDD/day demonstrated a lower risk for CRC (aHR: 0.32; 95% CI, 0.16–0.61) than those receiving ≥1 DDD/day (aHR: 0.45; 95% CI, 0.33–0.61), indicating that higher daily doses did not confer additional chemopreventive benefit. Continuous exposure modeling identified approximately 0.75 DDD/day (equivalent to about 80 mg/day) as the threshold at which CRC risk reduction was maximized, with no further reduction at higher doses. The protective association was statistically significant in UC while there was a similar but nonsignificant trend in CD, likely reflecting smaller event counts in that subgroup, the authors noted. Subgroup analyses showed aHRs <1.0 across all subgroups by age, sex, comorbidity strata and baseline medication use. Sensitivity analyses applying stricter exposure thresholds (≥90 and ≥180 cDDDs/year), excluding users of nonaspirin antiplatelet agents, restricting to continuous users without prescription gaps >90 days and restricting to patients with at least eight years of disease duration all yielded consistent protective estimates (aHR range: 0.36–0.46).

Details

Study Design: Nationwide propensity score-matched retrospective cohort study
Funding: Lo-Hsu Medical Foundation, Lotung Poh-Ai Hospital
Allocation: Observational; propensity-matched
Setting: Multicenter
Level of Evidence: 2b