This multi-center randomized controlled phase II trial will investigate the impact of stereotactic fractionated radiotherapy to the resection cavity of complete resected recurrent glioblastoma on progression free survival. As secondary endpoints, overall survival, safety and toxicity as well as early response criteria on MRI, quality of life and neurocognitive function will be assessed. Chemotherapy will not be part of the protocol, however, additional treatment will be possible upon investigators best choice.