SPDL1 and brain neoplasm: Considering that the sPD-L1 level may be associated with the tumor burden and the aggressive biological activities of tumors, we investigated whether there were associations between the baseline level of sPD-L1 and the tumor grade or Ki-67 expression, and finally demonstrated that the baseline level of sPD-L1 was significantly elevated in patients with advanced brain tumors or in patients with Ki-67 > 27.5%.