For instance, the American Cancer Society indicated a yearly PSA retesting for all patients with a value ≥ 2.5 μg/L at baseline, whereas other CPGs lowered the threshold to 1.0 μg/L, restricted the monitoring to men aged 55–69 years, and/or extended the time interval for PSA rescreening to 2–4 years [1,2,3,5]. Here, KLK3 is linked to cancer.