CHI3L1 and central nervous system cancer: Of note, it is reported that serum levels of YKL-40 in patients with glioma are related with tumor grade and burden [14], and high YKL-40 expression is associated with poor survival of patients with lung cancer, glioblastoma, colorectal cancer, hepatocellular carcinoma, gastric cancer [15–18], supporting the notion that elevated YKL-40 expression may serve as a useful potential biomarker of prognosis for cancer patients.