CD4 and neoplasm: In KRS-SCC tumors, we observed a preferential expansion of Tregs in CD4+ TILs, which appeared to occur in the DLN-TR group already (Figure 4D and 4F, DLN-TR), suggesting the influence of tumor microenvironment not only on TILs but also on T cells in nearby lymphoid organs, probably by affecting antigen presentation or tolerance mechanisms [37, 38, 51].