KLK3 and prostate cancer: The Prostate Health Index (PHI; Beckman Coulter, Brea, CA, USA) is used to predict the likelihood of detecting ≥ GG 2 prostate cancer at biopsy by combining the levels of free PSA, total PSA, and the [-2] form of proPSA (p2PSA) in a composite score using the following formula: ([-2]proPSA/free PSA) X √PSA (Table 1, Figure 1).