ICOS and esophageal squamous cell carcinoma: Tim3+ TILs tended to predict favorable prognosis of ESCC patients (P = 0.072), whereas no impact on survival prognosis was observed for LAG-3+ TILs (P = 0.185), OX-40+ TILs (P = 0.159) or ICOS+ TILs (P = 0.122) (Additional file 4).