Prognostic stratification of patients with nasopharyngeal carcinoma based on tumor immune microenvironment

BACKGROUND: Little is known about immune-related prognostic factors in patients with nasopharyngeal carcinoma (NPC). METHODS: We retrospectively reviewed 66 patients with NPC. Epstein-Barr virus (EBV) status, programmed cell death-ligand 1 (PD-L1) expression, and tumor-infiltrating lymphocyte (TIL) densities were analyzed, and a prognostic evaluation of these immune-related parameters was performed. RESULTS: The multivariate analyses demonstrated that CD8-positive TIL density but not PD-L1 expression on tumor cells or immune cells was a significant predictive factor for progression-free survival (PFS) and overall survival (OS). Subgroup analyses demonstrated that a positive PD-L1 expression on tumor cells in combination with a higher CD8-positive TIL density was significantly associated with favorable prognosis, whereas positive PD-L1 expression on tumor cells with lower CD8-positive TIL density was associated with worse prognosis. CONCLUSION: Our results suggest that PD-L1 expression on tumor cells in combination with CD8-positive TIL density could be a useful predictive biomarker for risk stratification in patients with NPC.