Objective:To investigate the change of collagen fibers in locally recurrent esophageal squamous cell carcinoma after radical chemoradiotherapy and the discrepancy of adverse effects and survival outcomes among groups with different salvage treatments, provide references for the options of salvage therapy.Methods:Medical records of 137 patients with esophageal squamous cell carcinoma who received radical chemoradiotherapy and had local recurrence admitted to Cancer Center of Renmin Hospital of Wuhan University from January 2015 to September 2022 were retrospectively collected. The expression of collagen fibers in paraffin samples of cases with different recurrence time was determined by Masson staining, and the differences of the average optical density were calculated. According to the salvage treatment after local recurrence, all cases were divided into the salvage surgery group, second-course chemoradiotherapy group and immunochemotherapy group. The differences of survival outcomes and incidence rates of esophageal tracheal fistula, hemorrhage, pericardial effusion, radiation pneumonitis, radiation esophagitis were analyzed among the three groups. The differences of survival rates were analyzed by Kaplan-Meier method and compared by log-rank test among groups.Results:The expression of collagen fibers in recurrent esophageal squamous cell carcinoma was significantly higher than that in primary esophageal squamous cell carcinoma. Collagen fiber expression was gradually down-regulated with the prolongation of recurrence time. The expression of collagen fibers in recurrent cases after 7 years was similar to that of primary esophageal squamous cell carcinoma. The 1-, 2- and 3-year survival rates of patients in the salvage surgery group, the second-course chemoradiotherapy group and the immunochemotherapy group were 47%, 30%, 20%; 50%, 27%, 15% and 72.5%, 50%, 50%, respectively; Immunochemotherapy was more effective in salvage treatment for recurrent esophageal squamous cell carcinoma, but there was no statistical difference.Conclusions:Collagen fibers are abundant in recurrent esophageal squamous cell carcinoma after radical chemoradiotherapy. With prolongation of recurrent interval, the expression of collagen fibers is down-regulated. The survival outcomes of patients in the immunochemotherapy group, salvage surgery group and second-course chemoradiotherapy group were comparable.