SPDL1 and telomere syndrome: The purpose of the present retrospective study was to evaluate correlations between serum sPD-L1 levels and clinicopathological parameters and to elucidate whether sPD-L1 levels and PD-L1 expressed on tumor cells can be used to distinguish the malignant phenotype in soft tissue tumor patients and to predict recurrence, metastasis, or prognosis in STS patients.