CD274 and osteosarcoma: In our study, we systematically investigated the expression patterns of PD-L1, PD-L2, and PD-1 in sarcomas including osteosarcoma, chondrosarcoma, synovial sarcoma, and giant cell tumors (GCTs) and further evaluated the association between PD-L1, PD-L2, and PD-1 expression and clinical prognosis of osteosarcoma to provide a therapeutic strategy guide.