However, in addition to prostate cancer, raised PSA levels are encountered in benign prostatic hyperplasia (BPH), prostatitis and normal prostate tissue, the PSA test has a fairly flat receiver operator characteristic curve, resulting in false positive and negative results meaning it is relatively poor at predicting or excluding significant prostate cancer [1, 2], which drives the need for more specific circulating biomarkers in its diagnosis. Here, KLK3 is linked to prostatitis.