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PCA3 Test
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PCA3 Test

I am a 67 year old Caucasian.My PSA is 3.3 up from 2.2 a year ago,PCA3 value was 48%.I had a needle biopsy and am waiting on the results.What is the significance of the PCA3 and do you consider it a reliable test?
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Avatar_m_tn
Hi,
PSA has improved the early detection of prostate cancer. However, it is specific for prostate and not prostate cancer – so there are overlaps with benign prostate enlargement.
PCA3, is likewise prostate specific, but the margin between cancer and non-cancer seems to be wider than for PSA and so, it is a promising test.
PCA3 is a new marker undergoing validation. This means that it is being compared with PSA in patients. Put another way – would PCA3 help judge who should get a biopsy and who should not?
The research on PCA3 has involved small numbers, and so obtaining an estimate for reliability is difficult to do. At the present time, there is no evidence that shows it will fail.
One of the faults of biomarkers in general is that there may be some normal tissue that interferes with the results. For PCA3 – the kidney expresses some of it normally. But there seems to be large difference in levels, so setting the right level to trigger a biopsy.
Another concern, is the degree of technology that would be required to deploy the test. If it is not feasible outside a research or academic center – the test may also not be useful.
Inquire from your doctors regarding PCA3, there may be other reasons the test was performed (more than as an aide to judge whether you should have the biopsy).
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Avatar_m_tn
What does a 48% value mean to you?
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Avatar_m_tn
Hi,
As I said, the test is not yet standard. I could give you a more meaningful answer if I knew what specific test was performed. Is this from urine? blood? prostatic fluid?
The basic item measured by these tests is the presence of the gene, usually a copy number. The 48% may indicate the ratio of gene copies and the amount of mRNA (this is a translated DNA). It may also mean a percent score based on the amount of PCA3 gene copies measured.
SInce the test is not yet standardized, the usefulness of the test will actually vary by simply changing what level will be used as the cut-off. For example, if we use 90% as the cut-off positive level to warrant a biopsy, we'll end up with most biopsies yielding positive (a high specificity value). But we'll also end up with some men not getting a bipsy, but getting cancer anyway. If we use a low cut-off, most cancers will be detected (a high sensitivity value)- but at the expense of some men who are otherwise normal getting biopsied and being declared as benign. The standardization is all about balances.
A study in urine estimates that if we used a score of 43 (not sure if this is the same with your %) to decide who should get a biopsy, we'll end up with 1 out of 3 men with cancer escapes the biopsy (and goes undetected) and 1 out of 5 men getting a biopsy when he has benign prostate enlargement.
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Avatar_m_tn
My PCA3 test came back showing a positive result.Does this always indicate cancer?
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Avatar_m_tn
Hi,
The answer would vary if you use actual prostate tissue, prostatic fluid, or urine. I'm assuming you had a DRE and a urine sample was subsequently sent.
Among all patients in general (this is without considering shifting the cut-off as I noted in the previous post) with a positive result - about one in three will not have cancer. That is why the biopsy would still be needed to make a diagnosis.
On the practical side, the biopsy would also yield additional information aside from whether or not cancer is present - and it seems we can't do away with it at the present state of the science.
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Avatar_n_tn
I am 68.  Last October I had a prostate infection.  During an annual physical in mid November my PSA was 22.  My doctort said it was not unusual and would come down in few months.  In January iwas 5.1 and in early March it was 4.1.  I do not get up in the night to urinate and do not seem to hav other symptoms. My urologist now wants to perform a biopsi on my prostate.  I am concerned about the dangers of this.
Hughd
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