The usual criteria for clinical prostate cancer are the results from the combination tests, which include the initial serum PSA (total PSA) test, abnormal results from a digital rectal examination (DRE), and the follow-up tests of either the more invasive needle biopsy or the less invasive—yet more expensive—Multi-Parametric MRI (MP-MRI). Here, KLK3 is linked to prostate carcinoma.