High PD-L1 expression is associated with a favorable prognosis in patients with esophageal squamous cell carcinoma undergoing postoperative adjuvant radiotherapy

Previous results on the prognostic value of programmed death-ligand (PD-L)1 expression in patients with esophageal squamous cell carcinoma (ESCC) remain limited and conflicting. The present study aimed to determine whether PD-L1 expression status predicts prognosis in patients with ESCC, particularly in those undergoing different postoperative treatments. Immunohistochemical staining for PD-L1 was performed on surgical specimens that were obtained from 246 patients with ESCC, who underwent surgical treatment but did not undergo preoperative chemotherapy, radiotherapy, targeted therapy or immune therapy. The association of PD-L1 expression with the clinicopathological factors and the association of PD-L1 expression with survival of patients with ESCC, including subgroups of patients undergoing different postoperative treatments (surgery alone, surgery with adjuvant chemotherapy, surgery with adjuvant radiotherapy and surgery with adjuvant chemo-radiotherapy groups), were statistically analyzed. Positive PD-L1 expression was significantly associated with advanced tumor-node metastasis stage (P=0.022). Median overall survival (OS) time was compared between patients with positive PD-L1 expression and those with negative PD-L1 expression in the overall patient population. In patients who were treated with postoperative adjuvant radiotherapy, the prognosis was significantly improved in patients who were PD-L1-positive compared with those who were PD-L1-negative (P=0.046). In patients treated with adjuvant chemotherapy, median OS was poorer in patients with positive PD-L1 expression compared with those with negative PD-L1 expression. However, the difference was not significant. Multivariate Cox regression analysis demonstrated that PD-L1 expression status was not an independent prognostic factor in patients with ESCC. High PD-L1 expression was associated with a favorable prognosis in patients with ESCC undergoing postoperative adjuvant radiotherapy, and it was concluded that patients with positive PD-L1 expression might benefit from postoperative adjuvant radiotherapy.