PROGENSA PCA3, the world's first gene-based urine test developed in the United States, is a molecular genetic screening of the urine. PCA3 (Prostate Cancer gene 3) is a gene that is expressed exclusively in the prostate tissue and is passed in the urine. In case of metastization, the gene is especially active, and the prostate carcinoma cells form 60 – 100 times more PCA3 than normal prostate tissue.
While the procedure is technically very involved, the actual test is comparably simple: after a massage is given to the prostate within the scope of the palpation, the patient will urinate. The previously administered massage causes the prostate cells to be discharged with the urine. The urine sample will then be send to a specialized laboratory to determine the PCA3 score. In the laboratory, a so-called transcription mediated amplification (TMA) will be performed, and within 15 to 30 minutes, the RNA in the urine sample will be quantified a billion-fold. Two enzymes specifically fitted to the PCA3 messenger RNA, will then yield the grade of concentration in the PCA level.
Above a score of 35, according to the producer GenProbe, there should be about a 50% chance that within the framework of a biopsy tumor tissue will be found. Above a score of 100, the hit rate is allegedly about 70%.
Current studies showed that with elevated PCA3 scores, a prostate biopsy often is more positive, meaning that cancer cells in the prostate are present. However, a low PCA3 score points to a lower possibility of a positive biopsy. This means that the urine test differentiates more accurately between prostate cancer and benign prostate diseases, such as a benign prostate hyperplasia or prostatitis (inflammation of the prostate).
Suitable candidates for a new urine test are in particular patients, who persistently elevated PSA score after a negative biopsy, and who are still suspected of having prostate cancer based on an elevated PSA score.
However, a negative test result cannot completely rule out the presence of a tumor in the prostate. The PCA3 test does consequently not a replace a biopsy, but is rather an addition screening method in the diagnostic spectrum.
Also for patients with a large prostate, it can be meaningful to take the PCA3 test, since often the PSA scores are often elevated without the presence of a carcinoma.
Obviously the more aggressive the cancer, the higher the PSA score. In the future, this could be helpful in deciding whether a prostate tumor must be treated or may just remain under observation.
The cost for a PSA screening is between 300 and 350 Euro, and currently the test is not paid for by any health insurance.