KLK3 and prostate cancer: Active surveillance (AS) is a preferred treatment strategy for appropriate patients with low-risk prostate cancer.1,2,3,4,5 Although surveillance protocols vary, prostate-specific antigen (PSA) testing and a periodic repeated staging biopsy are the 2 primary methods for detecting disease progression.6 Biopsies are effective for definitively demonstrating disease progression through pathologic upgrading, yet they are invasive and associated with a substantial risk of infection.1