We found a strong positive correlation of IDO-positive TILs, CD3-positive T lymphocytes, and INF-γ mRNA-producing TILs in the tumor microenvironment of EACs showing significantly better overall survival (47.7 vs. 22.7 months, p < 0.001) with emphasis on early tumor stages (pT1/2: 142.1 vs. 37.1 months, p < 0.001). Here, IDO1 is linked to neoplasm.