Inclusion Criteria:  Age ≥ 18 years Karnofsky Performance Status ≥ 70 Newly diagnosed cerebral or cerebellar lesion (contrast enhancing on a T1-weighted MRI scan) amenable to total resection with no dural attachment Frozen section confirming a metastasis of an extracranial (i.e. non-CNS) tumor Adequate distance to optic nerve(s), chiasm and brainstem (organs at risk for radiotherapy) Adequate birth control  Exclusion Criteria:  Leptomeningeal spread and dural attachment (assessed pre- and intraoperatively) Frozen section reveals primary CNS tumor, lymphoma, SCLC (Small-cell lung cancer) or germinoma More than one brain metastasis Psychiatric or social condition potentially interfering with compliance Contraindication against anesthesia, surgery, MRI and/or contrast agents Pregnant or breast-feeding women