Low-dose aspirin can reduce colorectal cancer mortality after surgery: A 10-year follow-up of 13 528 colorectal cancer patients

Background and Aim The chemopreventive effect of aspirin in colorectal cancer (CRC) is well studied, but its benefit in patients after CRC diagnosis and surgery is unclear. This study aims to investigate the effects of low-dose aspirin use in mortality among CRC patients after surgery. Methods Patients were analyzed in two cohorts: (i) patients taking aspirin before CRC diagnosis and continued or discontinued aspirin after surgery and (ii) patients, who never used aspirin before CRC diagnosis, received or did not receive aspirin after surgery. CRC-related mortality and all-cause mortality were the primary and secondary outcomes. Sub-distribution hazard ratio (SHR) for competing-risk CRC mortality was fitted to adjust for other causes of death; hazard ratio (HR) was used to compare all-cause mortality. Results A total of 13 528 CRC patients were included. Among 3292 patients with regular aspirin use before CRC diagnosis, 2658 (80.7%) continued aspirin and 634 (19.3%) discontinued aspirin after surgery. Continuous use of aspirin significantly reduced CRC-related mortality (SHR: 0.69, 95% confidence interval [CI]: 0.59-0.81) and all-cause mortality (HR: 0.61, 95% CI: 0.55-0.68). Among 10 236 patients who did not use aspirin before CRC diagnosis, 1054 patients (10.3%) received aspirin after surgery and 9182 (89.7%) did not. Aspirin initiated after surgery reduced CRC-related mortality (SHR: 0.88, 95% CI: 0.80-0.98) and all-cause mortality (HR: 0.87, 95% CI: 0.81-0.94). Conclusions Irrespective of aspirin use before surgery for CRC, low-dose aspirin after surgery lowers risk of both CRC-related mortality and overall mortality.