CD8A and neoplasm: In combination with the increased density of CD8 in the PD-L1-positive group in the hepatic metastases, we considered that the discordance of CD8 between primary tumor and liver metastases should be a concomitant state of differential PD-L1 expression, and that the tumor differentiation which is closely related to tumor heterogeneity may be the intrinsic driver of this discordance.