SPDL1 and central nervous system cancer: Elevated concentrations of circulating sPD-L1 were found in many cancers compared to controls, - in two separate studies of gastric cancer (GC) (34, 35) in hepatocellular carcinoma (HCC) (36) lung adenocarcinoma (37) clear cell renal cell carcinoma (ccRCC) (12), in different types of carcinomas (38), ovarian cancer (OC) (39), glioma (40, 41).