Tpex Subsets in Negative Tumor Draining Lymph Nodes for Predicting the Efficacy of PD 1 Inhibitors in Advanced or Recurrent Esophageal Squamous Cell Carcinoma

Inclusion Criteria: * Aged ≥18 years * Histologically confirmed esophageal carcinoma * Clinical stages IV based on the 8th AJCC TNM classification, or recurrent esophageal cancer * plan to treated with PD-1 immunotherapy * Eastern Cooperative Oncology Group(ECOG) performance status: 0-2 Exclusion Criteria: * Esophageal perforation or hematemesis * Any active autoimmune disease or a history of autoimmune disease * Disease progression occurs within 3months after PD-1 immunotherapy. * Allergic to macromolecular protein preparations, or to any of the ingredients in PD-1 inhibitors for injection. * Uncontrolled heart diseases or clinical symptoms * Congenital or acquired immunodeficiency (such as HIV infection); active hepatitis B (HBV-DNA≥104 copy number/ml) or hepatitis C (positive hepatitis C antibody, and HCV-RNA is higher than the detection limit of the analytical method); active tuberculosis.