Prognostic Value of YKL-40 in Patients with Glioblastoma: a Systematic Review and Meta-analysis.

YKL-40 is the most highly expressed gene in glioblastoma compared with normal brain tissues. Previous studies assessing the association between YKL-40 and survival in glioblastoma patients reported varying magnitude of estimates. The objective of this meta-analysis was to determine the prognostic value of YKL-40 in glioblastoma patients. PubMed and Embase databases were searched for studies relating to YKL-40 and prognosis of glioblastoma patients. Studies reporting estimates for overall survival by YKL-40 expression in glioblastoma patients were considered eligible. A meta-analysis of included studies was performed using fixed- or random-effect model to calculate the pooled hazard ratio (HR) and 95 % confidence interval (95%CI). Eight studies were ultimately considered eligible and included into the meta-analysis. Those eight studies included 1241 glioblastoma patients. Meta-analysis of those studies showed that high YKL-40 expression was associated with worse overall survival in glioblastoma patients (HR = 1.46, 95%CI 1.33-1.61, P < 0.001). Meta-analysis of studies with adjusted estimates and high quality showed that high YKL-40 expression was independently associated with worse overall survival in glioblastoma patients (HR = 1.50, 95%CI 1.35-1.66, P < 0.001). Both subgroup analysis and sensitivity analysis validated the obvious association between high YKL-40 expression and worse overall survival in glioblastoma patients. High YKL-40 expression is independently and markedly associated with worse overall survival in glioblastoma patients. YKL-40 is a good predictive biomarker of prognosis in glioblastoma patients.