Independent prognostic role of PD-L1 expression in patients with esophageal squamous cell carcinoma

Accumulating evidence has shown that PD-L1 expression is associated with clinicopathological features in various human malignancies. We searched for correlations between PD-L1 expression and clinicopathological data in esophageal squamous cell carcinoma (ESCC) patients. PD-L1 expression in primary tumors from 278 patients was evaluated using immunohistochemistry (IHC) in ESCC tissue microarray. Survival curves were constructed by using the Kaplan-Meier method. Univariate and multivariate Cox proportional hazard regression models were performed to identify associations with outcome variables. Overall, tumoral PD-L1 expression (≥10%, 20% or 30% as cut-off value) was associated with favorable DFS and OS upon multivariate analysis. When the patients stratified into stage I-II (168, 60.4%) and stage III-IV (110, 39.6%), or with lymph node metastasis (133, 47.8%), the prognostic role was not consistent. In patients with stage I-II disease, tumoral PD-L1 expression (≥5%, 10%, 20% or 30%) was associated with better DFS and OS upon multivariate analysis. In patients without lymph node metastasis, tumoral PD-L1 expression (≥1%, 5%, 10%, 20%, or 30%) was associated with improved DFS and OS in univariate or multivariate analysis. However, PD-L1 expression was not correlated with prognosis in patients with stage III-IV disease or with lymph node metastasis. Our results for the first time showed the prognostic role of tumoral PD-L1 expression was variable in different stages and lymph node status of ESCC. Tumoral PD-L1 expression was independent favorable predictor in ESCC patients with Stage I-II disease or without lymph node metastasis, not in stage III-IV or lymph node metastasis.