The study has been approved by the Medical Ethics Committee (METC Zuid-West Holland/Erasmus Medical Center; MEC-2020-0812). The results will be published in peer-reviewed academic journals and disseminated to patient organisations and media. conditions: Glioblastoma conditions: Glioblastoma Multiforme conditions: Glioblastoma, IDH-wildtype conditions: Glioblastoma Multiforme of Brain conditions: Glioblastoma Multiforme, Adult conditions: Recurrent Glioblastoma conditions: Astrocytoma, Malignant conditions: Astrocytoma of Brain studyType: OBSERVATIONAL observationalModel: COHORT timePerspective: PROSPECTIVE count: 464 type: ESTIMATED name: Re-resection name: Temozolomide name: Lomustine name: Re-irradiation name: Experimental therapy name: Best supportive care measure: Overall survival measure: Neurological morbidity at 6 weeks measure: Neurological morbidity at 3 months measure: Neurological morbidity at 6 months measure: Progression-free survival measure: Residual tumor volume measure: Quality of life at 6 weeks (EORTC QLQ C30) measure: Quality of life at 3 months (EORTC QLQ C30) measure: Quality of life at 6 months (EORTC QLQ C30) measure: Quality of life at 6 weeks (EORTC QLQ BN20) measure: Quality of life at 3 months (EORTC QLQ BN20) measure: Quality of life at 6 months (EORTC QLQ BN20) measure: Quality of life at 6 weeks (EQ-5D) measure: Quality of life at 3 months (EQ-5D) measure: Quality of life at 6 months (EQ-5D) measure: Serious Adverse Events sex: ALL minimumAge: 18 Years maximumAge: 90 Years stdAges: ADULT stdAges: OLDER_ADULT facility: University of California, San Francisco status: RECRUITING city: San Francisco state: California zip: 94143 country: United States name: Mitchel Berger, MD PhD role: CONTACT lat: 37.77493 lon: -122.41942 facility: Massachusetts General Hospital status: RECRUITING city: Boston state: Massachusetts zip: 02114 country: United States name: Brian Nahed, MD PhD role: CONTACT lat: 42.35843 lon: -71.05977 facility: University Hospital Leuven status: RECRUITING city: Leuven country: Belgium name: Steven De Vleeschouwer, MD PhD role: CONTACT lat: 50.87959 lon: 4.70093 facility: University Hospital Heidelberg status: RECRUITING city: Heidelberg country: Germany name: Christine Jungk, Dr. med. role: CONTACT lat: 49.40768 lon: 8.69079 facility: Technical University Munich status: NOT_YET_RECRUITING city: Munich country: Germany name: Arthur Wagner, MD role: CONTACT lat: 48.13743 lon: 11.57549 facility: Erasmus MC status: RECRUITING city: Rotterdam state: Zuid-Holland zip: 3015 CE country: Netherlands name: Arnaud Vincent, MD PhD role: CONTACT phone: +31639428949 email: a.vincent@erasmusmc.nl name: Jasper Gerritsen, MD role: CONTACT phone: +31629119553 email: j.gerritsen@erasmusmc.nl lat: 51.9225 lon: 4.47917 facility: Medical Center Haaglanden status: RECRUITING city: The Hague state: Zuid-Holland zip: 2261 CP country: Netherlands name: Marike Broekman, MD PhD role: CONTACT phone: +31639758253 email: m.broekman@haaglandenmc.nl lat: 52.07667 lon: 4.29861 facility: Inselspital Universitätsspital Bern status: NOT_YET_RECRUITING city: Bern country: Switzerland name: Philippe Schucht, MD PhD role: CONTACT lat: 46.94809 lon: 7.44744 hasResults: False