Analysis was done by SPSS v. 18. Overall as well as progression free survival were analysed with the Kaplan-Meier-method. Differences between the survival of two groups were analysed using the log-rank test (univariate statistics). Univariate cox regression analysis was used to compare categorical variables. Overall survival was defined as time from surgery to death. Progression free survival was defined as time from the start of radiotherapy to the evidence of progression according to the RANO-HGG-criteria or to death. If patients were alive at the time of our analysis (01.12.2016), survival times were censored to the date of the last follow up visit.