Expression and clinical significance of programmed death ligand 1 in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) has the highest incidence of all types of head and neck cancer in China. The present study aimed to investigate the association between the expression of programmed death ligand 1 (PD-L1) in NPC tissues and clinicopathological features, as well the outcomes for NPC patients. In addition, the association between tissue expression of PD-L1 and immune components in peripheral blood was assessed. The expression of PD-L1 was determined by immunohistochemistry, while immune indexes were determined by ELISA and flow cytometry. The positive expression rate of PD-L1 in NPC patients was 29.2%, and the PD-L1 expression levels were associated with distant metastasis (P=0.010) and the T-stage of the primary tumor (P=0.032). The expression of PD-L1 was associated with the distant metastasis-free survival of NPC patients (P=0.006). In addition, a statistically significant association of PD-L1 expression with Epstein-Barr virus viral capsid antigen IgA (EBV VCA-IgA; P=0.046) and with CD3^-CD19⁺ cells (P=0.014) was identified. These results indicated that PD-L1 may be a potential prognostic biomarker for NPC patients, and that EBV VCA-IgA and CD3^-CD19⁺ cells may be useful for predicting PD-L1 expression when its levels cannot be detected due to the lack of a tumor tissue sample.