Clinical and prognostic significance of HIF-1α in glioma patients: a meta-analysis.

Gliomas are the most common brain tumors, leading to significant cancer-related mortality worldwide. Hypoxia-inducible factor 1-alpha (HIF-1α) was shown to be involved in the pathophysiology and management of glioma, and might offer a therapeutic target. However, the results remain inconclusive. The purpose of this study was to systematically investigate the clinical and prognostic significance of HIF-1α expression in patients with glioma. Relevant studies published between 2000 and 2015 were searched in the electronic databases. The odds ratio (OR), risk ratio (RR) and mean difference (MD) with their 95% confidence intervals (CI) were employed to calculate the strength of significance. Finally, a total of 24 articles were retrieved, including 1422 glioma patients. No significant heterogeneity was presented between studies (I(2)<50%, P>0.01). Overall, our results showed that HIF-1α expression was significantly associated with high WHO grade (III+IV) of glioma (OR=8.59, 95% CI=6.56-11.24, P<0.00001). This significant relationship was also found between HIF-1α expression and microvascular density (MD=26.32, 95% CI=14.48-38.16, P<0.0001), overall survival (OS) (3-year OS: RR=0.48, 95% CI=0.35-0.66, P<0.00001; 2-year OS: RR=0.53, 95% CI=0.38-0.73, P<0.0001; 1-year OS: RR=0.79, 95% CI=0.66-0.95, P=0.01), and the cumulative survival time. However, HIF-1α expression was not associated with age and gender of glioma patients (P>0.05). In conclusions, our results suggested that HIF-1α expression was associated with high grade of glioma and OS, indicating that HIF-1α could predict prognosis and provide clinical insights into the therapeutic strategy for patients with glioma. More studies concerning other populations are also needed in the future research.