MGMT and central nervous system cancer: The RT options available to elderly patients with a good status, low-grade gliomas, isocitrate dehydro-genase (IDH) mutations, epidermal growth factor receptor (EGFR) amplification, 1p/19q deficiencies or O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation considerably vary if these patients are carefully monitored[46, 47].