KLK3 and cancer: For Gleason score 7 patients, it is clinically useful to distinguish between 4 + 3 = 7 and 3 + 4 = 7 patients since they have different clinical outcome and NCCN recommends most patients with Gleason score 4 + 3 = 7 to take immediate treatment, while the choice of treatment or surveillance in patients with Gleason score 3 + 4 = 7 depends on other factors such as cancer stage, PSA, and biopsy core.