This study aimed to determine whether the immune prognostic index (ECIPI), based on hemoglobin (Hb) and neutrophil‐to‐lymphocyte ratio (NLR), could predict the prognosis in patients with advanced esophageal squamous cell carcinoma (ESCC) receiving programmed cell death‐1 (PD‐1) inhibitor treatment. This evidence concerns the gene GSTM1 and esophageal squamous cell carcinoma.