Increased levels of sPD-L1 were found in the CSF of glioma patients (1.3202 ng/mL, 0.0925–22.0392 ng/mL; p = 0.003) compared with that of meningioma patients (0.1538 ng/mL, 0.0475–0.3157 ng/mL) (Table 4 and Figure 1B). Here, SPDL1 is linked to central nervous system cancer.