The Prostate Cancer Working Group 3 (PCWG3) defines this condition when PSA levels increase 25% from the nadir, considering only a rise of at least 2 ng/mL; whereas, according to the European Association of Urology (EAU), two consecutive values of PSA higher than 0.2 ng/mL are indicative of biochemical progression [4,5]. The gene discussed is KLK3; the disease is prostate cancer.