CD274 and gastrointestinal stromal tumor: Previous findings showed that tumor PD-L1 expression, evaluated via immunohistochemistry (IHC) on formalin-fixed and paraffin-embedded tumor sections, was greater in GISTs than in several types of soft tissue sarcomas [56], and the PD-L1 expression level was also associated with high-risk GIST patients showing poorer outcomes in therapeutic settings [57].