A Clinical Study Of Camrelizumab With Or Without Radiotherapy In The Treatment Of Esophageal Cancer

Inclusion Criteria: * 1\. Volunteer to participate in clinical research: fully understand and know the research and sign the Informed Consent Form (ICF); willing to follow and have the ability to complete all trial procedures; * 2\. Recurrent or metastatic esophageal cancer confirmed by histology or cytology, patients with ≤4 metastatic lesions; * 3\. Progress after first-line chemotherapy; * 4\. There are lesions measurable according to RECIST standards * 5\. Age ≥18 years old and ≤75 years old, regardless of gender * 6\. ECOG physical strength status score is 0～2; * 7\. Have not received immunotherapy or biological therapy before; * 8\. Hemoglobin ≥90g/L, platelets ≥10×109/L, absolute neutrophil count ≥1.5×109/L; * 9\. Serum creatinine ≤1.25 times UNL or creatinine clearance ≥60 mL/min; * 10\. Serum bilirubin≤1.5×UNL, AST (SGOT) and ALT (SGPT)≤2.5×UNL, alkaline phosphatase≤5×UNL; * 11\. No history of interstitial pneumonia or previous interstitial pneumonia; Exclusion Criteria: * 1\. Previously received anti-PD-1, anti-PD-L1, anti-PD-L2, anti-CD137 or anti-CTLA-4 antibody treatment, or any other antibodies targeting T cell costimulation or checkpoint pathways as specific targets or drug; * 2\. Have received radiotherapy in the past, and the tumor in the irradiation field has progressed; * 3\. Metastasis of meninges, pleura or pericardium; * 4\. Esophageal perforation and active esophageal bleeding, with invasion of trachea and large blood vessels in the thoracic cavity; * 5\. Patients with severe cardiovascular or pulmonary diseases, interstitial pneumonia or previous history of interstitial pneumonia: * 6\. Patients who cannot understand the test requirements or may not comply with the test requirements; * 7\. Autoimmune diseases (such as: systemic lupus erythematosus, rheumatoid arthritis, inflammatory bowel disease, autoimmune thyroid disease), but allow the following diseases to enter the next step of screening: type I diabetes, skin that does not require systemic treatment Diseases (such as vitiligo, psoriasis); * 8\. Active hepatitis B or C that requires treatment; * 9\. Suffered from an active infection requiring systemic treatment 14 days before the first administration; * 10\. Patients with other malignant lesions, except for curable skin cancer (non-melanoma), cervical carcinoma in situ or malignant disease cured ≥5 years; * 11\. The researcher believes that some obvious diseases should be excluded from this research; * 12\. The dose limit of radiotherapy cannot meet the limit requirement set by this study.