KLK3 and prostate cancer: Prediction models with a good performance are available, also in the setting of focal salvage HDR brachytherapy [56], in which other parameters have been described to be predictive of biochemical failure after focal salvage HDR brachytherapy for locally recurrent prostate cancer, such as gross tumor volume, pre-salvage PSA-value, and pre-salvage PSA doubling time [56].