Low-Dose Radiotherapy in Patients With Advanced Esophageal Squamous Cell Carcinoma Resistant to First-Line Chemotherapy Combined With Immunotherapy

Exclusion Criteria

• •Active autoimmune disease (e.g., inflammatory bowel disease, rheumatoid arthritis, systemic lupus erythematosus, vasculitis).
• •Symptomatic interstitial lung disease or active infectious/non-infectious pneumonitis.
• •Tumor invasion into adjacent organs (aorta or trachea) with high risk of bleeding or fistula; prior esophageal stent placement.
• •Other malignancies within the past 2 years (except adequately treated basal-cell carcinoma, cervical carcinoma in situ, etc.).
• •Active infection, heart failure, myocardial infarction within 6 months, unstable angina, or uncontrolled arrhythmia.
• •Any condition that, in the investigator's opinion, could interfere with study results or increase patient risk.
• •Mixed small-cell histology.
• •Pregnant or breastfeeding women.
• •Congenital or acquired immunodeficiency, HIV infection, prior organ or allogeneic stem-cell transplantation.
• •Active HBV, HCV, or tuberculosis infection.
• •Prior tumor vaccine or any live vaccine within 4 weeks (inactivated influenza vaccine is allowed).
• •Concurrent use of other immunosuppressive agents, chemotherapy, investigational drugs, or chronic corticosteroids.
• •Psychiatric illness, substance abuse, or social issues that could compromise compliance.
• •Prior intolerance, hypersensitivity, or contraindication to PD-1/PD-L1 inhibitors or chemotherapy components.