A correlation analysis of peripheral blood lymphocytes and tumor infiltrating lymphocytes in patients with oral squamous cell carcinoma found significant correlations regarding the level of total T lymphocytes (CD3+), helper T lymphocytes (CD4+), and cytotoxic T lymphocytes (CD8+), suggesting that circulating T cell levels could be an indicator for the local T cell-mediated antitumor responses [38]. Here, CD4 is linked to oral cavity squamous cell carcinoma.