Also shown in Table 3, EGFR (OR =0.56, 95% CI =0.33-0.94, P =0.03), HER3 (OR =0.42, 95% CI =0.24-0.72, P =0.002) and HER4 (OR =0.42, 95% CI =0.24-0.73, P =0.002) genes were more likely to be amplified in the patients with low-grade tumors as compared to those with high-grade tumors, suggesting that CNG of EGFR, HER3 and HER4 may be early-stage genetic events in glioma tumorigenesis. This evidence concerns the gene EGFR and central nervous system cancer.