KLK3 and prostate cancer: Prostate cancer patients are typically classified into different risk categories based on the prostate specific antigen (PSA) level, Gleason Score (GS) and T stage (tumor size) as low- (PSA ≤ 10 ng/ml, GS ≤ 6, T1 - T2a), intermediate- (10 ng/ml < PSA ≤ 20 ng/ml, GS = 7, T2b) and high-risk (PSA > 20 ng/ml, GS ≥ 8, T2c - T3a).