However, it should also be noted that the expression of the PD-L1 molecule is not an ideal marker, and among the many disadvantages associated with its technical staining, the most important seems to be a heterogeneous expression of this molecule through the tumor, its variability between primary and metastatic sites, and its dependence on the history of treatment (chemotherapy and radiotherapy could change PD-L1 expression on tumor cells) [11,12,13,14]. This evidence concerns the gene CD274 and neoplasm.