EGF and glioblastoma: At the same time, on the basis of glioma grade subgroup, we further compared the EGF +61G/A polymorphism in patients with glioblastoma and Grade I-III glioma, and found the OR value was greater than 1 (a versus A, OR = 1.28, 95% CI = 1.08–1.51; aa/Aa versus AA, OR = 1.30, 95% CI = 1.03–1.63), in the sense that by contrast to Grade I-III glioma, glioblastoma has the stronger associations with EGF +61G/A polymorphism (Fig. 4 and Fig. S3).