Invasive biopsy, in which tissue or fluid is removed from the prostate for subsequent testing, is still the most reliable method for diagnosing prostate cancer, while the digital rectal exam (DRE) and prostate-specific antigen (PSA) blood test remain the cornerstones for screening with multiparametric magnetic resonance imaging (mpMRI) for local staging [202]. Here, KLK3 is linked to prostate cancer.