PCA3 background information
PCA3: a gene-based test to help deciding if biopsy is really needed
The Prostate CAncer gene 3 (PCA3) Assay is a gene-based test. It is not a replacement for prostate specific antigen (PSA). It is an additional tool to help decide if in men suspected of having prostate cancer (PCa), e.g. those with a PSA between 2.5 and 10 ng/mL, prostate biopsy is really needed to diagnose PCa. PCA3 is, unlike PSA, prostate cancer-specific. This means that it is only produced by PCa cells and not affected by prostate size. It discriminates better than PSA between PCa and benign/non-cancerous prostate diseases such as benign prostatic hyperplasia (BPH, i.e. prostate enlargement) or prostatitis (infection of the prostate). Therefore, PCA3 gives very useful information, in addition to PSA, in deciding if biopsy is really needed.
A recent study suggests that the PCA3 Score can also differentiate between non-significant (indolent cancer) and significant PCa.
Interpretation of the PCA3 test result
The PCA3 Assay is a simple test: following a digital rectal examination (DRE), cancerous cells with high levels of PCA3 are shed from the prostate into the urine. A urine sample is then collected (click on animation to visualise). This urine sample is sent to a laboratory to determine the PCA3 Score. A high PCA3 Score indicates an increased likelihood of a positive biopsy, i.e. presence of cancer cells in the prostate. A low PCA3 Score indicates a decreased likelihood of a positive biopsy. If the PCA3 Score is low, a biopsy may be delayed or eventually avoided. In this way, the PCA3 Assay may help to avoid many unnecessary first biopsies and the potential discomfort and complications (pain, bleeding and infections) for the men involved.
The PCA3 Assay can also be used in men with one or more previous negative biopsies to predict the likelihood that another biopsy will be positive, or to assess the need for a next biopsy.
If a biopsy is performed and turns out to be positive, the PCA3 Score may be used as complementary information in predicting the pre-operative risk of PCa progression and the need for early treatment.