A statistical model based on a panel of 4K markers in blood-total, free, intact PSA and hK2, commercialised by OPKO Health Inc. (Miami, FL, USA) as the 4Kscore test can accurately predict Gleason 3 + 4 or higher prostate cancer on biopsy.11–14 The 4Kscore has also been shown to predict prostate cancer death in men followed for many years without screening.15,16 This suggests that the 4Kscore might aid risk stratification in patients with low- and intermediate-risk cancer on biopsy. Here, HK2 is linked to prostate carcinoma.