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

The goal of this observational study is to to determine whether patients with a high proportion of precursor exhausted T cells (Tpex) in negative tumor draining lymph nodes have longer overall survival. The main question it aims to answer is: Whether precursor exhausted T cells (Tpex) in negative tumor-draining lymph nodes have better predictive efficacy for treatment response than PD-L1 CPS.