Prostate Cancer Metastatic to Bone

The goal of this clinical trial is to learn if radiotherapy to the prostate and PET-positive (positron emission tomography) metastasis will lead to radiological response on PSMA-PET (prostate specific membrane antigen-PET). Patients who receive combined androgen deprivation therapy for de novo metastasized prostate cancer and show an incomplete PSA-response (\>0,2 ng/ml after six months) and exhibit at least four bone metastases on PET-imaging at this time point (without metastases to organs) can take part in this study. The main questions it aims to answer are: • Does radiotherapy to the prostate and PET-positive metastases lead to a radiological response one year after radiotherapy? Researchers will analyze PET-imaging prior to radiotherapy to the prostate and metastases and one yeare thereafter. Participants will: * Continue taking combined androgen-deprivation therapy * Receive a total of three PSMA-PET/CT scans * Receive radiotherapy to the prostate and PET-positive metastases * Visit the clinic every three months for 36 months * Complete quality of life questionnaires at every visit

PSMA-PET/CT or PSMA-PET/MRI are more accurate imaging modalities compared to CT/BS; in approximately 10-20% of high-risk patients diagnosed using conventional imaging PSMA-PET up-stages the disease. Therefore a substantial proportion of high-risk patients previously considered as non-metastatic are expected to be diagnosed with oligometastatic disease. While standard treatment pathways exist for patients with non-metastatic or oligometastatic disease confirmed using conventional imaging, less is known about the optimal management of patients with oligometastatic prostate cancer on PSMA-PET. Currently, data on the safety, effectiveness and oncologic outcomes of local therapies in oligometastatic patients diagnosed using PSMA-PET have been poorly reported so far. Thus, there is a need for a prospectively maintained database to collect real-world clinical data to produce high-quality research on the optimal management in oligometastatic prostate cancer who underwent PSMA-PET for primary staging and subsequent local therapy. This database will allow centers to retro- and prospectively collect data to facilitate analysis and assessment of the outcomes of oligometastatic patients managed with local therapy.