Currently, none of the clinical parameters (i.e., PSA and its derivatives such as PHI), biomarkers (i.e., PCA3), or combinations of biomarkers or clinical parameters (i.e., PCA3 combined with TMPRSS2:ERG, microRNA signatures, metabolomic biomarkers) used in clinical practice or reported in publications was able to diagnose PCa or stratify cancer risk with > 90% sensitivity and specificity, and AUC over 0.9, as shown in several recent reviews [2, 4–6, 8–10, 25–27]. Here, KLK3 is linked to cancer.