Initial reports showed that although prostate cancer and BPH patients showed no significant difference in hK2 levels, the ratio of hK2 to fPSA (%hK2) increased the accuracy over %fPSA in differentiating prostate cancer from BPH in men with PSA in the range of 4–10 ng/mL [88]. Here, HK2 is linked to benign prostatic hyperplasia.