CD4 and cancer: Although the present study focused on tumor‐infiltrating CD8+ T cells in OSCC, the type and functional status of immune cells, including CD4+ cells and FoxP3+ immunosuppressive T cells, and/or the tissue localizations of different tumor‐infiltrating immune cells can determine the balance between control or promotion of cancer.12 One antitumor mechanism employed by cytotoxic T cells requires that the cytotoxic cells physically contact cancer cells.39 This type of cytotoxic T cell may invade the tumor parenchyma, especially at the invading tumor edge, as observed in the present study.