Purpose: Programmed death ligand-1 (PD-L1) is the main ligand for programmed death-1 (PD-1), and is one of the major targets for cancer immunotherapy. Only a few studies are available for the clinical significance of PD-1/PD-L1 in nasopharyngeal carcinoma (NPC). There is a controversial association between PD-L1 expression and survival in NPC. This study aimed at defining any potential association between PD-L1 expression in tumor cells (TCs) and prognosis in NPC.
Patients and methods: A total of seventy NPC patients treated between January 2008 and December 2016 were included in the study. PD-L1 expression was assessed by immunohistochemistry (IHC) in tumor specimens. The IHC assay was considered positive if ≥5% of TCs are stained. Clinicopathological variables were documented. Variables included in the analysis were PD-L1 expression, clinicopathological characteristics, and prognosis.
Results: The estimated 5-year overall survival (OS) rate was 62%. Nearly 55.7% (n = 39) of the TCs tested positive for PD-L1 expression. No associations were found between the level of PD-L1 in TCs and clinicopathological characteristics. Comparisons between patients with PD-L1-positive tumors and PD-L1-negative tumors revealed that OS was statistically significantly longer in patients with PD-L1-positive tumors as assessed by the univariate Cox regression analysis (hazard ratio [HR], 0.378; 95% confidence interval, 0.158-0.905; P = 0.029) and Kaplan-Meier curves (P = 0.023).
Conclusion: PD-L1 expression is an important prognostic factor in NPC. PD-L1 expression positively correlates with survival.
Keywords: Expression; nasopharyngeal carcinoma; prognosis; programmed death ligand-1.