Prostate Cancer gene 3 (PCA3) is a gene-based test carried out on a urine
sample.
A non-coding mRNA located on chromosome 9q/21-22/.
It is highly specific to prostate cancer and this gene is over expressed in
over 95% of prostate cancer cases.
Results not affected by benign enlargement of the prostate (BPH) or prostatitis.
Up to 100 times more PCA3 is present in prostate cancer cells than non-cancerous
cells.
The test analyzes cells from the prostate found in the urine, after a firm and thorough digital rectal examination.
Following a digital examination the first urine sample is collectedand placed on ice and sent to diagnostic lab.
The result of the PCA3 test has to be taken into consideration along with the PSA measurement, a digital rectal examination, and any previous history of prostate studies.
A high PCA3 score indicates an increased likelihood of a prostate cancer, while a low score indicates a decreased likelihood of a prostate malignancy.
In a patient with an elevated PSA a low PCA3 is associated with only a 13% of high grade prostate cancer.
The score, ranging from 0-100, correlates with the probability of prostate cancer detection on subsequent transrectal prostate biopsies.
Studies have shown the score is independent of age, PSA level, or prostate size and is more effective in prostate cancer detection compared with PSA, or percent free PSA alone.
PCA3
Prostate cancer associated 3 (non-protein coding)(PCA3) also ref2242ed to as DD3) is a gene that expresses a non-coding RNA.
PCA3 is only expressed in human prostate tissue, and the gene is highly overexpressed in prostate cancer.
Useful as a tumor marker.
Compared to serum PSA, PCA3 has a lower sensitivity but a higher specificity and a better positive and negative predictive value.
It is independent of prostate volume, unlike PSA.
It should be measured in the first portion of urine after prostate massage with digital rectal examination.
It is useful to predict the presence of malignancy in men undergoing repeat prostate biopsy.
It could be useful clinically for a patient for whom digital rectal examination and PSA suggest possible prostate cancer, but the first prostate biopsy returns a normal result.
These findings occur in approximately 60% of cases, and on repeat testing, 20-40% have an abnormal biopsy result.
Correlates with adverse tumor features such as tumor volume, Gleason score or extracapsular extension, but studies have produced conflicting results.