Abstract: ob＜x＞jective To discuss the risk factors affecting recurrence within 3 years after synchronous radiotherapy for focal advanced esophageal squamous carcinoma, and construct a recurrence prediction risk model and validate it. Methods The data related to 156 patients with focal advanced esophageal squamous carcinoma who first visited the radiotherapy department of the Affiliated Hospital of Xuzhou Medical University from June 2017 to June 2019 were retrospectively analyzed. The 156 patients were randomly divided into training cohort (109 patients) and test ing cohort (47 patients) in the ratio of 7:3. Risk factors for recurrence within 3 years were counted and analyzed in the training cohort, prediction models were constructed using column line plots, and the predictive efficacy of the models was validated by applying calibration curves and clinical decision curves in the training and testing cohorts.Results Among 156 patients, 87 patients had histologically or imaging confirmed recurrence within 3 years, with a recurrence rate of 55.77%. The results of univariate and multifactorial analyses showed that SII ≥ 643.8, PNI < 48.05, presence of lymph node me＜x＞tastasis, and poor differentiation were independent risk factors for recurrence within 3 years after synchronous radiotherapy for locally advanced squamous esophageal cancer (p<0.05), and the above risk factors were included in the model. The calibration curve showed a good fit between prediction and reality, and the clinical decision curve suggested that most patients were clinically benefited.Conclusion This study is the first to discuss the effects of SII, PNI, and FAR on recurrence within 3 years after simultaneous radiotherapy for esophageal cancer, which can provide a reference basis for clinicians to comprehensively assess the disease and develop individualized follow-up monitoring programs for patients