An Observational Study on the Safety and Efficacy of Immunotherapy Combined With Concurrent Chemoradiotherapy in Elderly Patients With Esophageal Squamous Cell Carcinoma

Inclusion Criteria: * Voluntary participation with written informed consent. Age ≥70 years, regardless of gender. Histologically or cytologically confirmed ESCC. Inoperable or refusal of surgery, with tolerance for anti-tumor treatment. ECOG performance status 0-2. Expected survival ≥6 months. No severe abnormalities in hematologic, cardiac, pulmonary, hepatic, or renal function, and no immunodeficiencies. Exclusion Criteria: * No severe abnormalities in hematologic, cardiac, pulmonary, hepatic, or renal function, and no immunodeficiencies. Exclusion Criteria: Distant organ metastasis (excluding supraclavicular lymph nodes). Previous esophageal fistula, perforation, or pre-treatment for malignancy. Prior thoracic radiotherapy. Active autoimmune diseases or history of autoimmune diseases. Previous or ongoing PD-1 inhibitor treatment or participation in other interventional clinical studies. Allergy to large protein formulations or components of S-1 capsules. Uncontrolled cardiac conditions. Immunodeficiencies (e.g., HIV infection), active hepatitis B or C, or active tuberculosis. Active infection or unexplained fever \>38.5°C within 2 weeks before screening. History of other malignancies within 5 years (except cured basal cell carcinoma of the skin or cervical carcinoma in situ).