These results show that HMGB1 and IDO are closely related to NF-κB signaling pathway, suggesting that serum HMGB1 and IDO may be due to the increased expression of intracellular HMGB1 in ESCC, which may activate NF-κB signaling to promote the expression of IDO and release HMGB1 and IDO to the outside of cells. The gene discussed is IDO1; the disease is esophageal squamous cell carcinoma.