Real-world Experience of ICIs Plus Chemotherapy With or Without Radiotherapy for Advanced ESCC.

Inclusion Criteria: 1. Pathologically diagnosed as esophageal squamous cell carcinoma; 2. The clinical stage is IVb stage, that is, non-regional lymph node metastasis and distant organ metastasis (AJCC8th) of esophageal carcinoma. 3. Patients had received no previous systemic therapy 4. Patients who had received at least one cycle of first-line chemotherapy combined with immunotherapy, received or did not receive radiotherapy; 5. Complete medical records; 6. ECOG0-2; Exclusion Criteria: 1. Surgery for esophageal cancer; 2. Esophageal fistulae due to infiltration of the primary tumour. 3. Risk of gastrointestinal bleeding, oesophageal fistula or oesophageal perforation 4. Those who have a history of autoimmune disease or have been treated with immunosuppressants within the last 3 months. 5. Those who have received organ transplant surgery. 6. Patients with a previous history of malignant tumor (skin basal cell carcinoma and cervical carcinoma in situ) survived tumor-free for 3 years after treatment. Except for the above). 7. There are other serious diseases, such as myocardial infarction, cerebral infarction or severe cardiopulmonary insufficiency within 6 months