Prospective Evaluation of 68-Ga-prostate Specific Membrane Antigen (PSMA)-Positron Emission Tomograph (PET) and Early Prostatic Specific Antigen (PSA) Kinetics During Salvage Radiotherapy for Personalizing the Management of Men With Relapse of Prostate Cancer After Radical Prostatectomy

This is an open-label, phase II trial in patients with PSA recurrence after prostatectomy. Patients entering the study will all receive initial 50 Gray (Gy) radiotherapy (25 x 2Gy) to the prostate bed and thereafter be classified as either responders or non-responders depending on PSA response at fifth week of radiotherapy. A 68-Ga- PSMA-PET is done before start of radiotherapy, and analyzed before fifth treatment week in order to identify cancer lesions in patients with poor PSA response. Patients with PSA response after 5 weeks of radiotherapy will not receive any subsequent therapy, whilst patients with poor PSA response may be in need for additional therapy such as radiotherapy to lymph node metastases and/or boost fractions to local recurrence. Patients with more than 3 lymph node metastases or distant metastases will not receive any more radiotherapy, but individualized systemic therapy will be started.