High programmed death-ligand 1 expression is a poor prognostic indicator for esophageal squamous cell carcinoma and is correlated with two-field lymph node metastasis

BACKGROUND: This study detected programmed death-ligand 1 (PD-L1) expression in esophageal squamous cell carcinoma (ESCC) samples and investigated the association between the clinicopathological features of ESCC and PD-L1 expression. Furthermore, this study evaluated whether lymph node metastasis (LNM) status affected the prognosis of ESCC patients with diverse PD-L1 expression. METHODS: A total of 108 ESCC paraffin-embedded specimens were collected and further used to detect the expression of PD-L1 by immunohistochemistry. The correlation between PD-L1 expression and clinicopathological characteristics and its prognostic significance were evaluated. Finally, the clinical outcomes were investigated in the subgroup of patients with simultaneous high PD-L1 expression and LNM. RESULTS: PD-L1 expression was observed in 85.2% of ESCC cases, 43.5% of which showed high expression. Only N stage (P=0.038) was associated with high PD-L1 expression. Univariate and multivariate Cox regression analyses showed that T stage (P=0.012), N stage (P=0.029), and PD-L1 expression (P=0.044) were independent prognostic factors in ESCC patients. Moreover, further analysis of the N stage subgroup showed that skip LNM (P=0.286) or laryngeal nerve LNM (P=0.387) showed no prognostic significance, while two-field LNM was highly correlated with a worser 5-year overall survival (P=0.037). CONCLUSIONS: High PD-L1 expression was significantly correlated with N stage and can be used as an independent prognostic biomarker in ESCC. Its expression level can also be used to guide appropriate lymph node dissection in ESCC.