CD274 and lung cancer: The heterogeneity of PD-L1 expression in primary tumours has been studied by several methods in lung cancer, for which inconsistent results have been obtained.11,12 Elucidating intratumoural heterogeneity of the immune status of the tumour microenvironment could be helpful when considering the appropriateness of using endoscopically obtained biopsy samples for PD-L1 assessment in ESCC.