EGF and glioblastoma: We further compared the EGF +61G/A polymorphism in patients with glioblastoma and Grade I-III glioma, and found that glioblastoma has a stronger association with EGF +61G/A polymorphism compared with Grade I-III glioma, this means there is a significant association between the EGF +61G/A polymorphism and the malignancy of glioma.