PDCD1LG2 and neoplasm: In early-stage cases, the frequency of PD-L1- positive cases increased as the tumour progressed in depth, but PD-L2 did not have a relation with the depth; dividing cases into pT1a and pT1b cases by depth revealed that the positive rates of PD-L1 and PD-L2 were 10% and 25.7% for pT1a, and 36.7% and 30% for pT1b, respectively (Fig. 3d).