The Cluster Randomised Trial in over 400 000 men in the UK, using a single PSA test, reported similar prostate cancer-specific and all-cause mortality rates between screened men compared with controls when analysed at 10 years, but an increase in the proportion of men diagnosed with low-risk prostate cancer.4 Overdiagnosis, and the associated personal and economic costs of continued monitoring or ‘overtreatment’, has proved a significant barrier to the introduction of screening programmes based on PSA and standard transrectal biopsy. This evidence concerns the gene KLK3 and prostate carcinoma.