Therefore, we conducted a retrospective bicentric cohort study with regard to the following topics: 1) Is there a role for resection in subgroups of progressive GBM patients; 2) do patients with progressive GBM benefit from incomplete tumor resection and 3) which subgroups of patients may benefit from resection in terms of age, KPS, MGMT and other predictors of survival? Here, MGMT is linked to glioblastoma.