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

Objective. The 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 design. Immunohistochemistry 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. Results. In 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. Conclusion. Host 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. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2010; 109: 744-752)