The PCA 3 test (synonym: Prostate Cancer Gene 3) is a urine molecular genetic test.
Introduction
Prostate cancer (cancer of the prostate gland) is one of the most common cancers in men. Screening tests include:
- Digital rectal examination (DRU) – examination of the rectum (rectum) and adjacent organs with a finger (lat. digitus). An important part of the DRU is the palpation of the prostate.
- Transrectal prostate sonography – ultrasound examination of the prostate with a probe from the anus / rectum.
- Determination of PSA (prostate specific antigen).
- Biopsy (removal of a tissue sample from the prostate) from a PSA value of > 4 ng/ml.
However, with the above methods of investigation can not be presented all cases of disease or it results, as with the PSA value, more often false positive values.
A new test, the PCA 3 test, possibly closes this diagnostic gap. It was able to show higher hit rates than the PSA value in initial studies.
The method
The test is a urine molecular genetic test, meaning that genetic material (RNA) is detected. In the PCA 3 test, exfoliated cells of the prostate are analyzed in the urine. PCA 3 is a gene that occurs exclusively in the prostate gland. If degeneration of the cells occurs due to prostate cancer, this is expressed many times more.
Diagnostics
The examination is based on the quantifying measurement of the PCA 3 concentration and the PSA concentration. The quotient of the two values x10-3 yields the PCA 3 score (PCA3 score = PCA3 mRNA / PSA mRNA x 1,000), which, depending on the value, suggests further diagnosis by biopsy.
The probability of a positive biopsy result increases with the PCA3 concentration. The PCA3 score is thereby more informative than % free PSA for the predictive probability of a positive biopsy and correlates with the clinical stage (T2 versus T1) and the aggressiveness of the tumor (Gleason score > or = 7 versus < 7).
