Medical Journal of The Islamic Republic of Iran (MJIRI)

Background: Colorectal cancer poses a significant global health challenge, with high incidence and mortality rates. Neoadjuvant chemoradiotherapy (CRT) is standard for rectal adenocarcinoma to improve surgical outcomes and reduce recurrence, yet the overall treatment efficacy remains inadequate. This study investigates the effects of low-dose aspirin as an adjunct therapy during neoadjuvant CRT in rectal cancer patients.
   Methods: This non-randomized controlled trial included 90 patients with histologically confirmed Stage II or III rectal adenocarcinoma, allocated into two arms (45 each) receiving standard neoadjuvant CRT with or without 100 mg of daily oral aspirin. Primary outcomes included pathological complete response (pCR) rates, while secondary outcomes encompassed tumor regression grade (TRG) and tumor down-staging. Safety was assessed by monitoring aspirin-related adverse events. Comparisons between groups for the primary outcome and secondary outcomes were performed using chi-square tests.
   Results: The aspirin group exhibited a significantly higher pCR rate of 26.6% compared to 17.7% in the control group (P < 0.001). Down-staging analysis indicated favorable outcomes in the aspirin compared to the control arm (47% vs. 24%, P < 0.001). No significant adverse events related to aspirin were reported.
   Conclusion: Low-dose aspirin enhances the efficacy of neoadjuvant chemoradiation in rectal cancer patients, leading to improved pCR and tumor down-staging with minimal toxicity. These findings support aspirin's potential as a cost-effective adjunct to standard treatment protocols, warranting further investigation in larger trials.