KLK3 and Familial prostate cancer: <h4>Objective</h4>To estimate risk of prostate-specific antigen (PSA) relapse after radical radiotherapy (RT) for prostate cancer (PCa), and risk of PCa death after relapse according to Gleason score and time to relapse.<h4>Patients and methods</h4>Men in the National Prostate Cancer Register of Sweden who underwent primary radical RT in 2007-2024 were followed until 31 December 2024.