The effect of perioperative radiotherapy on prognosis in patients with operable rectal cancer who received neoadjuvant chemotherapy and underwent surgery.

Abstract

e15681 Background: Total neoadjuvant therapy has emerged as a contemporary treatment strategy for operable rectal cancer, aiming to enhance systemic disease control and improve surgical outcomes. While neoadjuvant chemotherapy constitutes a key component of this approach, the incremental benefit of adding perioperative radiotherapy remains unclear, particularly in terms of long-term survival. Evaluating the prognostic impact of perioperative radiotherapy in patients receiving neoadjuvant chemotherapy may clarify its role in optimizing local control and survival. This study aimed to assess the effect of radiotherapy on cancer-specific mortality in patients with operable rectal cancer who received neoadjuvant chemotherapy. Methods: This retrospective cohort study analyzed data from the Surveillance, Epidemiology, and End Results (SEER) database to identify patients with operable rectal cancer diagnosed between 2000 and 2022 who received neoadjuvant chemotherapy followed by curative-intent surgery. Patients were grouped according to perioperative radiotherapy use. Demographic, clinicopathological, and treatment related variables were extracted. Overall and cancer-specific survival were assessed using Kaplan– Meier analysis, and independent prognostic factors were evaluated using multivariate Cox proportional hazards regression. Results: The study was analyzed using data from 6404 patients. The proportion of male patients was 62%. The stage distribution at diagnosis for the patients included in the study was stage 1 (9.7%), stage 2 (26.8%), and stage 3 (63.5%), respectively. All patients had undergone primary tumor surgery, and all had received neoadjuvant chemotherapy. 44.9% of patients had elevated CEA markers at diagnosis. 433 (6.8%) patients died during follow-up. The 1, 3, and 5-year survival rates were 98.4%, 90.6%, and 83.4%, respectively. Factors affecting survival were evaluated using multivariate analysis, and the results were as follows: age (p < 0.001), gender (p = 0.028), race (p = 0.007), initial stage (p < 0.001), radiotherapy (p = 0.011), and CEA level (p < 0.001). Survival was better in patients who received radiotherapy (p: 0.011, HR: 1.68, 95% CI: 1.12-2.5). Conclusions: In this study, we evaluated the effect of radiotherapy on overall survival in patients with resectable rectal cancer. In stage 2 and stage 3 patients receiving neoadjuvant chemotherapy for resectable rectal cancer, radiotherapy improved overall survival. We found that the disease prognosis was worse in men, elderly patients, individuals of black race, and patients with high CEA levels at diagnosis.