Undetectable Concept Revisited

Now, so far it's just semantics.

But then you read all kinds of studies where they refer to PSA levels remaining undetectable for xxx time. Yet, they never seem to specify the test. Another example is the MSK nomograph. It has this:

Elevated Post-Radical Prostatectomy PSA

A lot, undoubtedly, is based on an individual case and the pathology report.  And also on the medical philosophy of the physician and patient.  Is it better to treat on the possibility of further increase in PSA, or is it better to wait and see.  This is perhaps the same kind of decision process behind how to treat an early cancer like mine.  Is it indolent?  Should I wait and see (Active Surveillance), should I treat with surgery, with radiation, or other treatment (including experimental treatments) ? 

One thing is certain:  prostate cancer is protean, perplexing disease. 

I thought that after SRT you may very well get a rise or two because there is a delay in the destruction of the cells. Then eventually (ideally) it goes down and down and reaches a nadir. Then you first start seeing what happens thereafter.

Do I have it wrong? Maybe someone else can chime in here?

Also, my point is that in so many studies/nomographs they talk about undetectable/detectable and time until it gets detectable. Well, my time is technically 0 months, but I suspect by some of their measures it is 12 months. It makes a difference when one attempts to try and draw some conclusions, especially concerning the probability of success with some treatments. Some studies do define detectable and it never seems to be the ultreasensitive measure.

Mel

If you consider the source, "undetectable" means the same thing for all tests - "less than the equipment/test will detect".

Of course it varies according to the lab, equipment, and test used.

My Uro/Surgeon does a standard test with Bostwick. Since surgery, it has been consistently <0.1, "undetectable".

My GP uses a different lab, and has changed labs since this all started. In his case, I have had two <0.01, "undetectable", and the last was 0.02.

For my GP, it is detectable.

For my Uro/Surgeon, it is undetectable.

Back to the Twilight Zone.

My question is not the definition of undetectable. We know what that means and it depends on the sensitivity of the test.

My problem is reading assorted articles when they talk about undetectable. Often they just do not define that in the article.

eg: Suppose an article said "based on our research we recommend further treatment as soon as the PSA becomes detectable"?

If their research involved the one-digit test, that would be a 0.1 threshhold. But maybe they are using a more sensitive test.

I wish all of these articles would be more specific!

Mel

If those who publish the studies don't say what their definition of undetectable is, I would expect that you, the questioning type, will email or write and ask them.

I tend to use the definition the uro gives me, as to use something else, and present him with something contradictory to his advice based on numbers at 2 or 3 decimal places, simply sets me up to have to go find another uro. I know some would argue that I need to be more aggressive, but to what end?

My opinion is:

I see little use for the 3-decimal accuracy. Going from 0.001 to 0.004 means nothing.

The 2 decimal accuracy is useful.

In my case, it has served as an early warning system where most likely I'll be starting SRT earlier, but in the face of a clear BCR. It also allowed me to see the radiation guy and get everything in place.

But I have paid a penalty in worry and anxiety. But I would still be anxious before every PSA test.

My doctors at Ford and at Umich all prefer the single decimal test.

Mel

Mel, I'll continue to hope that what looks like an upward trend in your numbers turns out to be some sort of temporary aberration.  I'm sure I'd probably be feeling the same kind of anxiety if I were in your shoes.  The disease is bad enough without the worry and anxiety.  Hang in there.

For what it's worth, my PSA readings taken at M. D. Anderson are not the ultrasensitive type but merely report "<0.1 = undetectable."

Prompted by an earlier discussion of this issue, I asked about ultrasensitive tests and was told that it was not uncommon to register very low levels of PSA after surgery but that anything under 0.1 ng/ml was "not clinically significant."  

I do not know - because I did not ask - whether they would switch to ultrasensitive tests once you passed 0.1 ng/ml.

Mel, I strongly suspect that "undetectable" for purposes of, e.g., the MSK nomographs is <0.1, but as someone already advised you, you could always email to find out.

Zen9