The Effect of the Appropriate Timing of Radiotherapy on Survival Benefit in Patients with Metastatic Esophageal Cancer Who Have Undergone Resection of Primary Site: A SEER Database Analysis

Abstract

Background. Metastatic esophageal cancer (MEC) is an advanced stage of esophageal cancer. However, still, resection of primary site and radiotherapy are considered treatment modalities to treat patients with MEC. Hence, this study is aimed at exploring the effect of the appropriate timing of radiotherapy on the survival benefit of these patients by comparing cancer-specific survival (CSS). Method. The patient information was obtained from the National Surveillance Epidemiology and End Results (SEER) database between the years 2004 and 2017. We used the SEER $\ast$ STAT (V8.3.9.2) software to search and download data. Patients treated with pre- and postoperative radiotherapy were divided into two groups. The propensity score matching (PSM) analysis was performed to increase the comparability of data within two groups. We used the Kaplan-Meier method to analyze and compare the CSS between the two groups. The Cox risk model was used to analyze variables affecting patient survival. Results. A total of 599 patients with MEC who experienced resection of the primary site and radiotherapy were recruited. 144 pairings formed through PSM. The 5-year CSS was 23.0% and 11.7% for patients who have undergone pre- and postoperative radiotherapy, respectively. Patients who have undergone preoperative radiotherapy showed better CSS than those who received postoperative radiotherapy ( $P<0.001$ ). The multivariate Cox analysis of the entire cohort showed that $\text{age}>60$ years at the time of diagnosis ( $\text{HR}=1.481$ , 95% CI: 1.1341-1.934, and $P=0.04$ ) and other histological types of esophageal cancer ( $\text{HR}=1.581$ , 95% CI: 1.067-2.341, and $P=0.022$ ) increased the risk of cancer-related death. Inversely, marriage ( $\text{HR}=0.696$ , 95% CI: 0.514-0.942, and $P=0.019$ ) and preoperative radiotherapy ( $\text{HR}=0.664$ , 95% CI: 0.517-0.853, and $P<0.001$ ) reduced the risk of death from cancer. Conclusions. For patients with MEC, preoperative radiotherapy might have a significant effect on the survival benefit over those who receive postoperative radiotherapy.