Considering the lack of association between the tissue and serum sPD-L1 levels on the one hand and the significant correlation between serum MMP-7 and sPD-L1 on the other hand, we hypothesize that the increased sPD-L1 levels are the consequence of an enhanced proteolytic tumor milieu rather than an increased PD-L1 expression of the tumor tissue. This evidence concerns the gene CD274 and neoplasm.