Therefore, this study continued to further explore the relationship between serum HMGB1, IDO and T lymphocyte functional phenotype, as well as the correlation between serum HMGB1 and IDO expression levels and prognosis of ESCC patients, in order to provide new ideas for clinical assistant diagnosis and immunotargeted therapy of ESCC. This evidence concerns the gene IDO1 and esophageal squamous cell carcinoma.