Patients (n = 85) treated with external beam radiotherapy between 1997 and 2013 following radical prostatectomy (RPE) with pathological tumour stage pT2c with positive surgical margins or pT3 and pT4 tumours with or without positive margins who presented with a postoperative and a preradiation prostate-specific antigen (PSA) level below 0.1 ng/ml. Here, KLK3 is linked to neoplasm.