KLK3 and cancer: However, within 10 years of radiotherapy, a quarter of patients will develop biochemical failure, a rise in serum prostate-specific antigen (PSA) highly suggestive of disease recurrence.1 Based on PSMA PET imaging, over 1 in 3 will have a localized recurrence that is confined to the prostate, a state independently predictive of subsequent metastasis and cancer-specific mortality.2,3 Salvage treatment directed to localized failures could improve upon these outcomes, a concept that has been demonstrated for various focal and whole gland salvage treatments.4–11