KLK3 and Familial prostate cancer: Data were collected from October 17, 1997, through September 14, 2021, with final analysis completed November 16, 2025.<h4>Exposures</h4>Baseline clinical and liquid biomarkers, including body mass index, waist-to-hip ratio, and glycated hemoglobin, together with prostate cancer-specific biomarkers of serum prostate-specific antigen (PSA) and magnetic resonance imaging-derived prostate volume and PSA density.<h4>Main outcomes and measures</h4>The primary outcome was long-term prostate cancer incidence.