Overexpression of vascular endothelial growth factor indicates poor outcomes of glioma: a systematic review and meta-analysis.

Background: Accumulated studies have revealed that vascular endothelial growth factor (VEGF) plays an essential role in the progression of glioma, but the prognostic significance of VEGF expression for patients with glioma remains unknown.

Method And Material: A literature search of public databases (PubMed, ISI Web of Science, Science Direct, Cochrane Central Register of Controlled Trials, Wiley Online Library, China National Knowledge Infrastructure, China Biology Medicine disc, Chongqing VIP and Wan Fang Data) was conducted. A meta-analysis was performed to evaluate the association between the overexpression of VEGF and the survival for the glioma patients. Subsequently we evaluated the impact of VEGF expression on the pathological grade of glioma.

Results: A total of 32 articles with 2307 cases contributed to this analysis, of which 31 reported overall survival (OS) and 5 reported progression-free survival (PFS). In this meta-analysis, VEGF overexpression significantly identified the unfavorable outcome on OS (HR = 1.647, 95% CI: 1.324~2.048, P < 0.001, Z = 4.48) but not on PFS (HR = 1.021, 95% CI: 0.974~1.070, P = 0.393). Subgroup analyses also revealed that high level of VEGF was associated with the poor OS for the patients with glioma according to region, case number, specimen type, method to detect VEGF and statistical method. Furthermore, the significant correlation was achieved between VEGF expression and the pathological grade of glioma (r = 0.307, P < 0.001).

Conclusion: This study suggests that VEGF expression is significantly correlated with the glioma progression and may be a valuable prognostic factor on OS for the glioma patients.