Inclusion Criteria:  Age ≥ 18 years, Karnofsky Performance Index ≥ 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. Informed consent.  Exclusion Criteria:  Leptomeningeal spread and dural attachment (assessed pre- and intraoperative). Frozen section reveals primary CNS tumor, lymphoma, SCLC or germinoma. Psychiatric or social condition potentially interfering with compliance. Contraindication against anesthesia, surgery, MRI and/or contrast agents. Pregnant or breast-feeding women.