3 current uses for test
10.04.11
Cleveland Clinic Laboratories
Background Information
Serum prostate specific antigen (PSA) is the standard
marker for diagnosis and management of prostate
cancer. While PSA is a useful marker available for this
disease, its utility is limited in many common clinical
situations. For screening purposes, PSA utility is
limited because it is prostate specific but not cancer
specific; consequently, there is no PSA lower limit of
detection for which the risk of prostate cancer is zero.
For predicting biologically significant disease, the
predictive value of PSA is limited because higher grade
tumors often express little PSA. Decisions regarding
the need for re-biopsy in men with an elevated PSA
are limited because PSA usually is more reflective of
prostate volume rather than the risk of carcinoma.
mRNA of the prostate cancer antigen 3 (PCA3) gene
has been shown to be over-expressed (median 66-fold)
in >95% of prostate cancer tissue compared with
normal or benign prostate tissue.1,2 PCA3 is prostate
cancer specific, and the PCA3 assay is unaffected by
prostate volume. Therefore, the PCA3 assay addresses
many of the issues related to PSA screening, improves
the sensitivity and specificity of PSA interpretation and
may add other information more reflective of tumor
biology. Low levels of PCA3 mRNA have been shown
to correlate with a low probability of biopsy-proven
prostatic adenocarcinoma.3,4
Clinical Indications
PCA3 is useful:
1. in conjunction with PSA screening of high-risk
individuals (those with positive family history),
where serum PSA may be normal and not reflect
true cancer risk;
2. in deciding on the need for re-biopsy in men with
elevated PSA and prior negative biopsy, as published
studies have demonstrated that, in this setting,
PCA3 improves diagnostic accuracy;
3. in the selection of men for active surveillance, as
published studies have demonstrated that PCA3
correlates with tumor volume and can help identify
those with biologically insignificant tumors.
Interpretation
PCA3 results are reported as a score ranging from
4 to 125, the ratio of PCA3 mRNA to PSA mRNA.
Likelihood of a positive biopsy increases as the score
increases.
A score of 35 is considered the cutoff for positive vs.
negative PCA3 result.
Methodology
The PROGENSA PCA3 assay (Gen-Probe, San Diego,
Calif.) is performed on a first-catch urine sample
collected following digital rectal examination of the
prostate gland. The assay combines RNA target capture,
transcription mediated amplification and hybridization
protection for both PCA3 and PSA RNA.
(this is a technical brief from the hospitals lab, Whats interesting is what this World Class Cancer Center uses the test for numbered 1-3.) I also wanted to add that I continue to see different opinions on why the panel was delayed. Its confusing reading the different news releases especially for investors who have an interest in the quick approval, I think I posted the before, but I spoke with the Immunology Panel and the delay was simply because they did not get all the documents copied and sent out to the panel in time. I commented that I would take a few weeks off work and Copy whatever they needed and hand deliver each packet, I do however see it written that GPRO sent additional information in but from what I am told that was not the case.