MGMT and glioma: The high recurrence rate stems from multiple factors: the infiltrative growth pattern of GBM prevents complete surgical removal (7); the blood-brain barrier restricts delivery of large molecules and poorly lipid-soluble drugs (8) and the prevalent emergence of resistance to radiotherapy develops through various mechanisms, including the presence of quiescent glioma stem cells (GSCs), protective peritumoral brain (PTB) tissue (9) and intact DNA repair systems in O6-methylguanine-DNA methyltransferase(MGMT) unmethylated gliomas (10).