Approximately 1 in 6 American men will develop prostate cancer at some point in his lifetime, making prostate cancer the most commonly diagnosed cancer in this patient population. Currently, prostate cancer screening involves digital rectal examination (DRE) along with measurement of serum prostate-specific antigen (PSA) levels. However, the specificity of PSA screening is low, and approximately 60% to 80% of men referred for follow-up will have a negative biopsy. The prostate cancer antigen 3 gene (PCA3) was discovered in a search for more specific biomarkers of prostate cancer that could facilitate screening and early diagnosis of the disease. The PCA3 gene, which is located on chromosome 9 at band q21 to q22, produces a noncoding messenger RNA of unknown function. Expression of PCA3 is markedly increased in more than 95% of malignant prostate
tumors. In contrast, there is little to no expression of PCA3 in nonprostatic tissues or in other types of malignancy. PCA3 transcripts are detectable in prostate tumor cells shed into the urethra after palpation of the prostate by DRE. As a result, first-catch post-DRE urine specimens may be used to test for PCA3 expression. The earliest versions of PCA3 detection tests used reverse transcription polymerase chain reaction (RT-PCR) amplification or nucleic acid sequence-based amplification (NASBA), while the assay currently used by most laboratories in the United States utilizes transcription-mediated amplification (TMA).