Radiotherapy Combined With Immunochemotherapy in Metastatic Esophageal Squamous Cell Carcinoma

Inclusion Criteria: 1. Age ≥18; 2. Metastatic esophageal squamous cell carcinoma (stage IVB, M1) confirmed by pathology; 3. ECOG performance status: 0-1 point; 4. No prior anti-tumor treatment; 5. Adequate hematologic, renal, hepatic, and cardiac functions that meet the requirements for chemotherapy and immunotherapy assessed by investigators. Exclusion Criteria: 1. Non-squamous cell esophageal carcinoma or ESCC mixed with other pathological types of esophageal cancer; 2. Patients who are potentially curable with surgery as assessed by investigators; 3. Pleural metastasis or malignant pleural effusion, pericardial effusion; 4. Any prior anti-tumor therapy for esophageal cancer, i.e., surgery, radiotherapy, chemotherapy, or immunotherapy; 5. High risk of gastrointestinal bleeding, esophageal fistula, or perforation; 6. Patients with Patient-Generated Subjective Globe Assessment (PG-SGA) score≥9; 7. Unstable cardiac diseases or symptoms; 8. History of interstitial pulmonary disease, non-infectious pneumonitis; pulmonary fibrosis, or other uncontrolled acute pulmonary disease; 9. Active autoimmune disease or history of autoimmune disease; 10. Conditions of immunodeficiency or active infection requiring systemic therapy; 11. Pregnant or breastfeeding; 12. Patients with synchronous second primary cancer and a history of malignancy within the past 5 years (excluding completely cured cervical carcinoma in situ or basal cell or squamous cell skin carcinoma).