A PSA test can reduce the relative risk of mortality from prostate cancer by approximately 20% when repeated at 2- to 4-year intervals.3 However, it will miss a proportion of clinically significant prostate cancers (underdiagnosis) while identifying clinically insignificant prostate cancers (overdiagnosis) that do not require treatment.4,5. This evidence concerns the gene KLK3 and Familial prostate cancer.