Tumor-infiltrating CD8+ T-cell density is an independent prognostic marker for oral squamous cell carcinoma.

BACKGROUND: The presence of tumor-infiltrating lymphocytes (TILs) is associated with improved survival in head and neck squamous cell carcinoma. However, the prognostic value of TILs remains unclear in oral squamous cell carcinoma (OSCC). METHODS: We evaluated the associations between tumor-infiltrating CD8+ T-cell density and survival in five distinct compartments in 139 OSCC cases. RESULTS: There was a significant association between increased tumor-infiltrating CD8+ T cells and their distribution. High parenchymal CD8+ T-cell density at the invading tumor edge was associated with improved overall survival (OS) and disease-specific survival (DSS; P < 0.01 and P < 0.01, respectively). High stromal CD8+ T-cell density at the tumor periphery was also associated with improved recurrence-free survival (RFS; P < 0.01). Cox regression analysis revealed that high stromal CD8+ T-cell density at the tumor periphery and high parenchymal CD8+ T-cell density at the invading edge were independent prognostic makers (hazard ratio: 0.38 and 0.19, 95% confidence interval, 0.18-0.80 and 0.05-0.72, P = 0.01 and 0.01, respectively) for RFS and OS, respectively. CONCLUSIONS: Assessment of CD8+ T cells at the parenchyma of the invading edge and peripheral stroma provides an indicator of tumor recurrence and prognosis.