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Question about PSA rise after surgery

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Posted 12/24/2009 5:45 PM (GMT 0)
Just curious:

I thought I read that 0.2 is kind of the danger point. If the PSA is >=0.2 after surgery, one should consider something like salvage radiation.

But with the super-sensitive PSA tests, I keep reading about folks who have 0.01 then 0.02 and then maybe 0.04. So now the PSA is doubling say every 2-3 months, yet it is below 0.20. In fact, I've also read that a PSA < .1 is often considered zero.

So, I'm confused. Can someone clarify. Is the above scenario a recipe for more treatment or is it still considered 0. I can see why the super-sensitive PSA can cause a lot of grief!

Mel

 

Posted 12/24/2009 5:51 PM (GMT 0)
A whole lot of opinion is in these interpretations. I don't think you will find a document that says anyting less than .1 is undetectable, otherwise, they wouldn't detect it.

Maybe from a practicality and medical payout point of view, it is hard to attack every case that goes from .01 to .o4 to ???.

It seems from a logic point of view that any movement in the PSA upwards is indicative of something going on, if nothing less than a small portion of prostate that was left behind.

Goodlife
Posted 12/24/2009 7:28 PM (GMT 0)
I can't speak to most subparts of your question, but I can say something from experience about the part where you say that <.1 is often considered zero.

At my cancer center those of us who are considered at relatively lower risk for biochemical recurrence are given the old standard PSA tests, which are less expensive than the super-sensitive PSA tests. I think it's also an issue re insurance reimbursement. Anyway, for the regular tests, the lower limit for detecting PSA is 0.1 ng/ml. Thus, a negative test result is <0.1 = "undetectable."

That's the way it was explained to me. Hope that helps, at least a little.

Zen9
Posted 12/25/2009 9:28 PM (GMT 0)

The answers to your questions are tied to an understanding of the lower limits of the test methods.  You spoke of two different types of PSA tests, and the primary difference is the lower limits of the measurement capability.

Probably the most important thing to understand, first, is that there is no such thing as "zero" PSA.  The standard PSA test has a lower measurement limit of 0.1 ng/mL.  Anything less than that is not "zero"; rather, it is simply "undetectable."  Neurovascular nerve bundles, for example, will produce a trace amount of PSA, but below the measurement threshold of the standard PSA test.  If you read about guys joining the "zero club", this simply means they have PSA below the test measurement cabability...not really zero.

The ultrasensitive test goes roughly an order of magnitude lower, into the hundredths.  This test is newer and more expensive.  Some surgeons will prescribe the ultrasensitive tests after surgery, and particularly if they saw or have reason to believe there might be cancer left behind.  There is no "right" or "wrong."  If they do prescribe the ultrasensitive test, they are interested in getting a "track record" of PSA levels to see if it rises over time.  If it does start moving in an upward trend, then the patient will be better prepared for planning SRT, salvage radiation therapy.  Some surgery patients will have measurable levels of PSA on the ultrasensitive test; other patients will be below detectable levels.

There is no threshold set in concrete when all medical professionals agree that biochemical reoccurrence has taken place, but you are correct in understanding that the most commonly agreed level is 0.2ng/mL.

Does this information help?

Posted 12/25/2009 10:47 PM (GMT 0)
Compiler,
As Casy explained there are different sensitivities of testing which came about as equipment improved. It's probably easier to think in terms of the original equipment as the "standard" test which could only detect levels above 0.3 (therefore if PSA was not detected it was reported as <0.3). I don't believe this level of testing is used any longer. The equipment was later much improved and gave a 10 fold increase in sensitivity. Think now of it as the "sensitive" test. This could detect PSA down to .03 but again if PSA was undetectable it technically would be reported as <0.03. In the late 90's the equipment was much improved again with a further 10 fold increase in sensitivity over the "sensitive" test. Now we're talking "ultra-sensitive" test. This can detect PSA down to .003-------if PSA is not detected it technically should be reported as <0.003. But each of these test levels was prone to a slight degree of error therefore it is common to see the sensitive test, if nothing is detected, reporting (for accuracy's sake) as <0.1 (undetectable) while if the the "ultra-sensitive" test is used and nothing is detected it is common to report it as undetectable i.e. <.01 (sometimes this also is simply reported as <0.1). Action (additional treatment) is not usually undertaken until there is clear evidence of an increasing PSA above 0.1. However there is an argument that such a recurrence could be observed much earlier as a steadily increasing PSA at the ultra-sensitive level.
There is a bit of reading here:

www.prostate-cancer.org/education/preclin/McDermed_Using_PSA_Intelligently2.html

under the headings "what is an ultra-sensitive PSA test" and "expected PSA levels after RP"

Bill
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