HOXD13 and central nervous system cancer: In the present study, we addressed three hypotheses through clinical comparisons and found the following: (a) sPD-1 and sPD-L1 levels in the circulation were higher in glioma patients than in healthy controls; (b) the levels were modified by surgical resection, and (c) sPD-1 and sPD-L1 in peripheral blood have the potential to predict glioma recurrence.