Heterogeneity was observed in the analysis of PD-L1 expression with histological differentiation (P = 0.002; I2 = 71%), the depth of tumour invasion (P < 0.001; I2 = 89%), lymph node status (P < 0.001; I2 = 81%), and tumour stage (P < 0.001; I2 = 92%). The gene discussed is CD274; the disease is neoplasm.