Radiotherapy Target Volume in Locally Advanced Esophageal Squamous Cell Carcinoma in the Immunotherapy Era

This retrospective real-world cohort study will evaluate the efficacy and safety of different radiotherapy target volume extents in patients with locally advanced esophageal squamous cell carcinoma. Patients who previously received definitive or preoperative radiotherapy, with systemic treatment consisting of concurrent chemoradiotherapy with or without immunotherapy, will be identified from existing medical records. The study will not assign or modify any treatment. Patients will be classified according to the radiotherapy target volume actually used in clinical practice, including the longitudinal gross tumor volume-to-clinical target volume (GTV-CTV) margin and the extent of regional lymph node irradiation. The study will compare locoregional recurrence-free survival, recurrence patterns, overall survival, progression-free or disease-free survival, treatment completion, treatment-related toxicity, lymphocyte reduction, and postoperative outcomes among different target volume strategies. The aim is to provide real-world evidence to support individualized radiotherapy target volume selection in locally advanced esophageal squamous cell carcinoma.