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.