A raised PSA level only has a 30% positive predictive value for cancer [4] and is more commonly associated with benign prostatic hypertrophy (BPH), conversely, 37% of men with a PSA reading in the normal range of 2.5–4 ng/ml still harbour prostate cancer [5], thus PSA screening is not routinely recommended [6]. Here, KLK3 is linked to cancer.