Impact of Aspirin on Recurrence Prevention After Curative Resection for Stage I–III Colorectal Cancer: A Multi‐Institutional Retrospective Study

BACKGROUND AND OBJECTIVES: Although multiple studies have reported the anti-tumor effects of aspirin on colorectal cancer, its benefit in patients with colorectal cancer following curative resection remains controversial. This study aimed to evaluate the effect of aspirin administration in patients with stage I-III colorectal cancer following curative resection. METHODS: This multi-institutional retrospective study included 2,863 patients with stage I-III colorectal cancer who underwent curative resection between January 2017 and December 2019. Patients were classified into two groups according to aspirin use. Clinical characteristics and oncological outcomes were analyzed. RESULTS: The aspirin group was older, and fewer patients had advanced pathological tumor stages or received postoperative adjuvant chemotherapy than non-aspirin group. Aspirin use tended to be associated with improved postoperative prognosis in patients with stage I-III colorectal cancer (overall survival: 91.1% vs. 80.9%, hazard ratio = 0.646, 95% confidence interval = 0.32-1.30; recurrence-free survival: 82.6% vs. 73.7%, hazard ratio = 0.730, 95% confidence interval = 0.44-1.20). After propensity score matching to minimize bias between groups, aspirin use was associated with improved postoperative prognosis (overall survival: 91.0% vs. 69.8%, hazard ratio = 0.306, 95% confidence interval = 0.14-0.68; recurrence-free survival: 82.4% vs. 56.6%, hazard ratio = 0.350, 95% confidence interval = 0.19-0.62). Aspirin use significantly improved recurrence-free survival in patients with advanced cancer who were recommended to receive postoperative adjuvant chemotherapy. CONCLUSIONS: This study suggests that aspirin use is associated with improved postoperative prognosis in patients with stage I-III colorectal cancer after curative resection. Aspirin may be beneficial for advanced-stage patients, for whom postoperative adjuvant chemotherapy is recommended.