VEGF levels in patients with glioma: a systematic review and meta-analysis.

Vascular endothelial growth factor (VEGF) has a crucial role in the angiogenesis of various tumors, including glioma. As the levels of VEGF would change in patients with glioma, we conducted the current systematic review and meta-analysis to more clearly determine the VEGF level alterations in different grades of glioma. PubMed and Scopus databases were sensitively searched for all the possible keywords addressing glioma and VEGF. Case-control and cohort studies on human subjects, which measured VEGF levels were eligible to be included in the study. Out of a total number of 3,612 studies, 22 studies were included and 12 studies entered the meta-analysis. This review revealed that serum levels of VEGF in glioma patients were 1.56 pg/dL higher compared to healthy controls (P = 0.05). Besides, immunohistochemistry (IHC) measurement of VEGF in surgical biopsies indicated significant difference in these two groups as well (P = 0.02). Yet, there was not a significant difference between patients with low-grade gliomas (World Health Organization (WHO) grades I-II, LGG) and those with high-grade gliomas (WHO grades III-IV, HGG) (P = 0.43). The results of this systematic review and meta-analysis demonstrate that VEGF levels would significantly increase in glioma, and therefore, could be potentially considered as a biomarker for this cancer.