Patients with primary GBM, aged 65 years or older, starting their first course of RT between 01/2009 and 12/2015, were extracted from the prospective patient’s registry of the local department for radiation oncology at the Technical University of Munich (TUM), Germany. For all patients, treatment decisions were consented within an interdisciplinary tumor board specialised for neuro-oncologic tumors. The median age of the 62 patients was 69.6 years (range 65.1-85.6 years). Since molecular marker evaluation became a standard for all patients only recently, this information was not available for all patients: IDH mutation status was available in 32 cases (51.6%) and was negative for all of these patients. MGMT methylation was tested in 37 cases (59.6%) with 15 cases of methylated MGMT promotor (40.1%) (Table 1).Table 1Patient characteristicsCharacteristicsRT (n = 27)RChT (n = 35)Age – years Median69.670.469.3 Range65.1–85.665.8–85.665.1–78.8Sex – no. (%) Male32 (51.6)9 (33.3)23 (65.7) Female30 (48.4)18 (66.6)12 (34.3)ECOG-Score – no. (%) 0909 (25.7) 1288 (29.6)20 (57.1) 21813 (48.1)5 (14.3) 366 (22.2)0 Missing101 (2.9)Extent of surgery – no. (%) Biopsy only7 (11.3)5 (18.5)2 (5.7) Subtotal resection34 (54.8)17 (68.0)17 (48.6) Gross total resection21 (33.9)5 (18.5)16 (45.7)MGMT-promotor Methylated – no.15411 Non-methylated – no.221012 Missing – no.251312Time from Surgery to RT (d) Median28.52928 Range12–6112–5814–61RT regimen (total/ single; Gy) 42/312120 40.05/2.67880 60/2 or 59.4/1.834331 other844Salvage Treatment – no.23320 Radiotherapy14014 Chemotherapy15114 Surgery14212