The PSA kinetics profile, including initial PSA level (iPSA) [9], time to PSA nadir (TTN) [9–12], nadir PSA level [9, 13, 14], PSA decline pattern [15–17], and PSA doubling time (PSADT) [18], had been shown to reflect tumor burden and predict outcomes in patients with prostate cancer under ADT. Here, KLK3 is linked to prostate cancer.