Association between the Epidermal Growth Factor +61G/A Polymorphism and Glioma Risk: A Meta-Analysis

BACKGROUND Gliomas account for almost 80% of primary malignant brain tumors. Epidermal growth factor (EGF) is an interesting research candidate in which to look for genetic polymorphisms because of its role in mitogenesis and proliferation. Extensive studies have found that a single nucleotide polymorphism (SNP) +61 G/A (rs4444903) in the EGF gene is associated with the susceptibility of glioma, however, the results have been controversial. Furthermore, the association between EGF +61 G/A polymorphism with the development and grade progress of glioma has not been established. METHODS We examined the association of EGF +61 G/A polymorphism and glioma by performing a meta-analysis. Nine studies testing the associations between EGF +61 G/A polymorphism and risk of glioma with 1758 cases and 2823 controls were retrieved. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the strength of the association. The pooled ORs were performed for the allele model, codominant model, dominant model, and recessive model, respectively. RESULTS Overall, this meta-analysis showed significant associations between the EGF +61 G/A polymorphism and glioma susceptibility in all four genetic models. However, in the stratified analysis by the grade of glioma, we only found this association existed in patients with Grade IV glioblastoma, but not in patients with Grade I-III glioma. We further compared EGF +61 G/A polymorphism in patients with glioblastoma and Grade I-III glioma accordingly, the stronger association between the EGF +61 G/A polymorphism and the malignancy of glioma was found. CONCLUSIONS The results of this meta-analysis suggested that the EGF +61 G/A polymorphism is associated with both the susceptibility of glioma and the malignance of glioma.