However, some studies have reported no difference in the levels of sPD-L1 between healthy donors and patients with a variety of tumors including NSCLC [62], glioma [20], esophageal cancer [63], triple-negative breast cancer [64], and bladder cancer [21], and a few studies have described lower levels of sPD-L1 in patients with nasopharyngeal carcinoma [65], early breast cancer [66, 67], gastric carcinoma [68], hepatocellular carcinoma [69], and clear cell renal cell carcinoma [70] compared to healthy donors. This evidence concerns the gene SPDL1 and central nervous system cancer.