Neoadjuvant Chemotherapy With/Without Radiotherapy for Locally Advanced Rectal Cancer: A Nationwide Retrospective Cohort Study

Background/Aim: The role of neoadjuvant radiotherapy in the management of patients with locally advanced rectal cancer (LARC) who have undergone neoadjuvant systemic therapy has been the subject of recent debate. Patients and Methods: We identified eligible rectal cancer patients diagnosed between 2011 and 2020 using data from the Taiwan Cancer Registry. In our primary analysis, we applied propensity score weighting (PSW) to balance observable potential confounders. We then compared the hazard ratio (HR) of death the neoadjuvant concurrent chemoradiotherapy (nCCRT) group and the neoadjuvant chemotherapy without radiotherapy (nCT) group. Additionally, we conducted a comprehensive assessment of other outcomes and performed various supplementary analyses. Results: The primary analysis included 2,298 patients. The overall survival did not exhibit statistically significant differences, with a PSWadjusted HR of 0.72 (95% confidence interval=0.33-1.56, p=0.40) when comparing the nCCRT group to the nCT group. These findings were consistent with those of other long-term outcomes and supplementary analyses. Conclusion: In patients with LARC who have undergone neoadjuvant systemic therapy, the addition of radiotherapy did not yield statistically significant differences in long-term clinical outcomes.