Tumor-infiltrating lymphocytes, particularly the balance between CD8+ T cells and CCR4+ regulatory T cells, affect the survival of patients with oral squamous cell carcinoma

ObjectiveThe objective of this study was to clarify the prognostic significance of tumor-infiltrating lymphocytes (TILs) in oral squamous cell carcinoma (OSCC); the present study analyzed various TIL-related parameters.Study designImmunohistochemistry was performed in 87 patients with OSCC for the following TIL-related parameters: nest-CD8+ T cells, stromal CD8+ T cells, CD4+ T cells, total regulatory T cells (Tregs), CCR4+ Tregs, ratio of nest CD8+ T cells/CCR4+ Tregs, and ratio of stromal CD8+ T cells/CCR4+ Tregs.ResultsIn univariate analyses, the following parameters were associated with decreased survival: few nest- and stromal CD8+ T cells and more stromal CCR4+ Tregs, but not total Tregs. Low ratios of nest and stromal CD8+ T cell/CCR4+ Treg were associated with worse survival. In multivariate analysis, the stromal CD8+ T cell/CCR4+ Treg ratio was an independent prognostic factor.ConclusionHost immune responses in the stroma of OSCC affect the survival of the patients. The in situ balance between effector T cells and regulatory T cells is the most important factor predicting survival.