KLK3 and prostate cancer: Advances in novel positron emission tomography (PET) radiotracers for prostate cancer, above all 68Gallium-labeled ligands of the prostate-specific membrane antigen (68Ga-PSMA) are associated with unprecedented sensitivity for localization of biochemically recurrent prostate cancer at low PSA levels as shown by several meta-analyses of retrospective studies (5) and lately by a prospective multicentre trial including 635 patients (6).