Current Radiotherapy Concepts Regarding Brain and Bone Metastases in Centers Participating in the German-Danish Interreg-Project TreaT

Background/Aim: Radiotherapy regimens for brain or bone metastases vary substantially. This study compared regimens utilized in Northern Germany and Denmark. Patients and Methods: Three centers participating in the Interreg-Project TreaT completed questionnaires regarding preferred radiotherapy regimens for brain or bone metastases. Results: Brain metastases: In poor-prognosis patients, all centers prefer short-course whole-brain irradiation (WBI) for multiple metastases. For oligometastatic disease, two centers prefer WBI, one center fractionated stereotactic radiotherapy (FSRT). For single lesions, all centers use FSRT. In intermediate- or favorable-prognosis patients, longer-course WBI is preferred for multiple lesions, sometimes with simultaneous-integrated boost. For oligo-metastasis, regimens vary. FSRT is preferred for single lesions. Bone metastases: For poor-prognosis patients, single-fraction radiotherapy is used for uncomplicated metastases and short-course radiotherapy for (impending) fractures, large soft-tissue components, and spinal cord compression. Multi-fraction regimens are preferred for intermediate-prognosis and longer-course regimens for favorable-prognosis patients. Conclusion: Regimens are relatively similar for bone metastases, single and multiple brain lesions, but vary considerably for few brain metastases. Further cross-border collaboration is required to provide more uniform and optimized treatment standards.