Abstract
Background: Radiation-based neoadjuvant therapy followed by radical surgery is the standard treatment for locally advanced rectal cancer (LARC), but things might have changed with the advent of total mesorectal excision (TME). This study re-evaluated the clinical efficacy of preoperative radiotherapy for LARC patients in the TME era by population-based analysis to identify any long-term survival benefits. Methods: LARC patients receiving preoperative radiotherapy or not followed by surgery between 2011 and 2015 were extracted from the Surveillance, Epidemiology, and End Results (SEER) database. Overall survival (OS) was analyzed by Kaplan-Meier curves, and potential candidates for preoperative radiotherapy were identified by nomogram. Results: There were 7582 eligible patients; 6066 received preoperative radiotherapy, and 1516 received non-preoperative radiotherapy. The initial result showed that the pooled hazard ratio (HR) for OS was in favor of preoperative radiotherapy compared with non-preoperative radiotherapy group (HR = 0.86, 95% confidence interval (CI) = 0.75-0.98, P <0.05). The cases were randomly divided into training and validation datasets, and multivariate Cox regression analysis of the training set determined that age, sex, carcinoembryonic antigen level, tumor stage, node stage, tumor differentiation, perineural invasion, and the number of dissected lymph nodes were independent risk factors for OS in the training set (all P <0.05). A nomogram was established based on the risk factors to predict the OS (concordance index, training set: 0.70, validation set: 0.67). Further analysis showed that the long-term survival of high-risk patients was better with preoperative radiotherapy (HR = 0.71, 95% CI = 0.56-0.91, P <0.05). Conclusions: Preoperative radiotherapy has long-term survival benefits for LARC patients, especially those with high risk.