KLK3 and cancer: Several clinical indicators (4–17), such as prostate specific antigen (PSA) (7–9), seminal vesicle involvement (10, 11), tumor volume (12–16), extraprostatic extension and other MRI features (17–21), and the Gleason score (22) predict clinical outcomes such as biochemical recurrence after treatment (4–6) and cancer metastasis (10, 11, 14).