Men diagnosed with what has classically been termed “intermediate-risk” prostate cancer (PCa)—based on Gleason score 7, prostate-specific antigen (PSA) 10−20 ng/mL, and clinical stage T2b or 2c disease—have highly variable clinical behavior and prognosis and are considered a broad, heterogeneous cohort for whom management recommendations cannot be standardized. Here, KLK3 is linked to prostate cancer.