Immediate Curative vs Conservative Treatment in Older Men With M0, High-risk Prostate Cancer

It is currently unclear if immediate curative treatment (radiotherapy or surgery) of high-risk prostate cancer without metastasis in older men (\>=75 years) generates the same survival benefits as in younger patients or if the harms/ side-effects of immediate curative treatment outweigh the benefits. In this study the investigators randomize older patients with high-risk, non-metastatic high-risk prostate cancer to either immediate curative therapy or to conservative, more problem-oriented therapy to investigate if immediate curative treatment prolongs life, improves quality of life and is cost-effective.

Inclusion Criteria: 1. Participant must be 75 years of age or older, at the time of signing the informed consent. 2. Participants who are healthy as determined by medical evaluation and geriatric G8/ miniCOGTM evaluation (G8: Fit, score \>14, or reversibly frail; miniCOGTM: score \>2) And who have PCa (diagnosed ≤6 months) with one or both of the following features: * Gleason grade 8-10 (ISUP group 4 and 5) other than microscopic, low-volume disease (tumor must be either palpable or visible on MRI, i.e., PIRADS 4 or 5) * Locally advanced PCa (T3 or T4) (unequivocal findings of clinical/ radiological T3 or clinical/ radiological T4 on DRE or MRI; broad capsular contact of tumor on MRI is treated as localized disease, T2, in the context of this study) * Able to read, understand and fill in HRQoL questionnaires (PROMS) 3. Male 4. Capable of giving signed informed consent as described in Appendix 1, which includes compliance with the requirements and restrictions listed in the informed consent form (ICF) and in this protocol. Exclusion Criteria: Medical Conditions 1. Dementia (unable to consent) Prior/Concomitant Therapy 2. Prior radiation to the pelvis 3. Hormone therapy \>3 months prior to randomization Diagnostic assessments 4. Lymph node metastasis (N0) on MRI, CT or PSMA-PET CT (equivocal N-findings =N0; borderline cases will be discussed and called by a study tumor board). 5. Distant metastasis (M0) on MRI, CT, bone scan or PSMA-PET CT (equivocal bone scan findings need to be confirmed with MRI or CT; borderline cases will be discussed by a study tumor board). Other Exclusions 6. Disabled or severe comorbidity (identified by G8 screening) 7. Unable to read, understand or fill out HRQoL questionnaires (PROMS)