CD274 and esophageal squamous cell carcinoma: In addition, 68 pathologists from 18 medical institutions were recruited to individually interpret four antibodies, namely, 22C3, SP263, SP142 and E1L3N, with the aim of investigating interobserver concordance of PD-L1 evaluation in esophageal squamous cell carcinoma, making comparisons between different antibodies, and further analyzing the factors affecting the concordance of interpretations.