Targeting cellular pathways altered in G4 astrocytoma, such as mammalian target of rapamycin (mTOR), epidermal growth factor receptor (EGFR) gene amplification, PTEN (phosphatase and tensin homolog) mutation and TP53 mutation, have also failed to improve the outcome [4]. This evidence concerns the gene PTEN and astrocytoma (excluding glioblastoma).