KLK4 and prostate cancer: Developments include algorithms around PSA isoforms (ie, the four-kallikrein and Prostate Health Index tests),4 and multifactorial risk-calculator nomograms, such as the Prostate Cancer Prevention Trial and European Randomized Study of Screening for Prostate Cancer.5 Urine in particular is an attractive noninvasive route, with the potential to reduce the number of patients subjected to prostate biopsy.