Patients With Metastasized Prostate Cancer Whose Prostate-specific Antigen-level (PSA) Remains >0,2 ng/ml After Six Months of Dual Antihormonal Therapy Will Receive Radiotherapy to the Prostate and Radiotherapy to Refractory Metastases

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

Sex

Male

Minimum age

18 Years

Maximum age

85 Years

Inclusion Criteria:

* Prostate adenocarcinoma
* de novo metastasized prostate cancer (at least 4 osseous metastases +/- lymphonodal metastases)
* first-line combined antihormonal therapy (ADT + ARPI) for six months
* PSA \> 0,2 ng/ml after six months of combined ADT/ARPI therapy
* multimetastasized disease stage without visceral metastases on imaging at first diagnosis (PET, CT, or bone scan)
* \<16 osseous/lymphnodal metastases on response assessment imaging (PSMA-PET/CT) after six months of combined antihormonal therapy

Exclusion Criteria:

* neuroendocrine histology
* visceral metastases (M1c)
* prior radiotherapy to the pelvis
* PSA \< 0,2 ng/ml after 6 months of combined antihormonal therapy
* prior prostatectomy
* contraindication against PSMA-PET/CT and/or radiotherapy to the prostate/metastases
* HIFU or TUR-P within 6 months of study treatment
* other active malignancy two years prior to study inclusion (except skin cancer in remission)
* relevant GU/GI condition (active fistula or other)
* known tumor predisposition syndrome