KLK4 and posterior cortical atrophy: Even with relatively new biological markers available, such as the TMPRSS2-ERG fusion gene, non-coding RNA (PCA3) [29], kallikrein included in basic PHI (prostate health index), or 4K tests [30,31,32], there is an urgent need for more accurate methods to risk-stratify men who present with symptoms of PCa in order to prevent the over-diagnosis and unnecessary treatment of patients with benign conditions.