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.