Men with a raised PSA may have no evidence of prostate cancer at biopsy, whilst not all men with prostate cancer have raised PSA: a third of men with PSA>10ng/mL showed no evidence of prostate cancer at sextant biopsy [4] whilst 63% of men with prostate cancer, and 41% of men with intermediate to high grade cancer (Gleason score≥7), had PSA<3ng/mL [5]. This evidence concerns the gene KLK3 and prostate carcinoma.