The number of IDO positive cells was not significantly higher in metastatic tumors (P = 0.079), but the number of IDO and TIGIT positive cells/mm2 correlated in both hot spots (R2 = 0.24, P < 0.01) and full tumor sections (R2 = 0.35, P < 0.01). This evidence concerns the gene TIGIT and metastatic neoplasm.