Survival differences between chemotherapy and chemoradiotherapy in metastatic esophageal cancer: a propensity score-matched study based on the SEER database

Background: The aim of this study was to explore the impact of chemotherapy (CT) and chemoradiotherapy (CRT) on prognosis in metastatic esophageal cancer (mEC) patients.Methods: Information of patients with mEC from 2010 to 2016 was retrieved from the Surveillance, Epidemiology, and End Results (SEER) database. Demographic and clinical data between CT and CRT groups were compared. Propensity score matching (PSM) analysis was used to reduce the influence of potential confounding factors. Multivariate Cox regression analysis was used to evaluate prognostic factors. Moreover, interaction tests and survival analyses were performed to determine whether pathological type conferred any survival benefits in subgroups.Results: A total of 3,352 mEC patients were recruited including 1,697 CT patients and 1,655 CRT patients. In multivariable Cox regression, marital status, gender and pathological type were identified as independent prognostic factors for mEC. There was no statistical significance between the CT group and CRT group in overall survival (OS) and cancer-specific survival (CSS) in the matched and unmatched cohort. In subgroup analyses, patients with esophageal adenocarcinoma (EAC) undergoing CT had favorable prognosis. However, in the subgroup of esophageal squamous cell carcinoma (ESCC), patients in the CT group had worse outcomes compared with patients in the CRT group.Conclusions: Patients with EAC and ESCC could respectively benefit from CT and CRT. Besides, we recommend individualizing the treatment strategy for mEC based on the pathological type.