We identified some sub-populations with higher survival benefit derived from IDO-1-expression in tumor cells: in particular, for patients with stage I disease OS HR was 0.27 (95% CI 0.09-0.81, p = 0.07), PFS HR was 0.35 (95% CI 0.12-0.97, p = 0.09); for patients with adenocarcinoma OS HR was 0.37 (95% CI 0.12-0.79, p = 0.003), PFS HR was 0.21 (95% CI 0.08-0.58, p = 0.023). Here, IDO1 is linked to adenocarcinoma.