Widely used biochemical, histopathological and clinical criteria, for example prostate-specific antigen (PSA) level, Gleason score, and the clinical tumour stage, have demonstrated a significant variability in predicting subgroups of prostate cancer patients with distinct clinical outcome (Miller et al, 2001; DeMarzo et al, 2003; Glinsky et al, 2004). Here, KLK3 is linked to prostate cancer.