Prostate cancer (PCa) is the second most common malignant disease in men worldwide (1) Suspicion for PCa is based on pathological digital rectal examination (DRE), prostate specific antigen (PSA) or magnetic resonance image (MRI) findings and indicates, as standard of care, a biopsy of the prostate (PBx) for histopathological verification (2). Here, KLK3 is linked to prostate cancer.