Salvage Stereotactic Body Radiotherapy of the Prostate Bed for Biochemical Recurrence After Radical Prostatectomy.

INCLUSION CRITERIA 1. Localized adenocarcinoma (cN0M0) of the prostate treated primarily with radical prostatectomy with definitive intent. 2. Either persistent PSA after prostatectomy (PSA ≥ 0.1 ng/mL at least 6 weeks after prostatectomy), or biochemical progression (two consecutive rising PSA amounts with a PSA \>0.1 ng/mL , or three consecutive PSA rises) 3. WHO PS 0-1 4. Age ≥18 years 5. Ability to understand and willingness to sign a study-specific informed consent prior to study entry 6. Ability to understand and answer the EPIC-26 form in one of the languages available EXCLUSION CRITERIA 1. Patients with a pT4 tumor at prostatectomy 2. Patients with previously pathologically confirmed N1 3. Patients with macroscopically involved margin at surgery (R2) 4. Patients with a history of distant metastases 5. Patients with a recurrence visible on imaging (local, pelvic, or distant). Pelvic nodes with a small diameter \>1cm and/or positive on PSMA without other explanation, are considered as a pelvic recurrence. 6. Latest PSA \> 2ng/ml 7. Patients with a IPSS \>20 8. Gleason 10 tumor 9. Prior history of high-intensity focused ultrasound ablation (HIFU), cryosurgery or brachytherapy of the prostate 10. Prior pelvic radiotherapy 11. Prior hormonal therapy started more than 6 weeks before randomization 12. History of inflammatory bowel disease, ataxia telangiectasia, prior rectal or bladder surgery. 13. Other active malignancy, except non-melanoma skin cancer, superficial bladder cancer, or malignancies with a documented disease-free survival for a minimum of 3 years before randomization.