The recently updated US Preventive Services Task Force guidelines recommended against serum prostate-specific antigen (PSA)-based screening for prostate cancer on the grounds that the expected harms of screening (false-positive findings, overdiagnosis, and overtreatment) outweigh the potential benefits.1 Conceptually, overdiagnosis is defined as detection by screening of tumors that would not have presented clinically in a person's lifetime in the absence of screening. This evidence concerns the gene KLK3 and prostate carcinoma.