EGFR and astrocytoma (excluding glioblastoma): On the contrary, loss of PTEN locus were more frequent in high-grade astrocytomas (49/65, 75.4%) than in low-grade astrocytomas (4/12, 33.3%) (p = 0.007), and EGFR amplification was only detected in high-grade tumors (26/73, 35.6%) (p = 0.002).