KLK3 and posterior cortical atrophy: Approaches used to enhance the predictive performance for PCa of PSA include use of PSA derivatives such as age-specific PSA, PSA density, and PSA velocity; various combinations of PSA molecular forms; and kallikrein biomarker–based risk algorithms such as the 4Kscore [14], prostate health index [15], and Stockholm-3 test [16].