KLK3 and prostate cancer: Meanwhile, published studies have shown that the Beckman Coulter Prostate Health Index (phi), which is a mathematical combination of total PSA, fPSA, and p2PSA (aforementioned as [−2]pro-PSA), as well as p2PSA and its derivatives, namely, %p2PSA, defined as (p2PSA/fPSA) × 100, may significantly improve the accuracy in the detection of prostate cancer over the PSA and the %fPSA [15, 108, 109].