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Undetectable Concept Revisited

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Posted 1/31/2011 6:06 PM (GMT 0)
Zen9:

It is not just MSK. There are quite a few articles that I have read where they do not define their type of PSA test. I guess I could email every time I see it, but it isn't worth it for me at this time.

My decisions are pretty clear regarding this next step.

I guess if my PSA only goes from 0.13 to say 0.15, then I may delay for another month.

Mel

Posted 1/31/2011 7:27 PM (GMT 0)
Compiler - I had just the same question you are asking here. I looked at a bunch of different journal articles, not just the abstracts, but the articles themselves. Most of the studies that are in the peer reviewed journals as you find on pubmed, etc. define undetectable as either .1 or .2, and they have held this threshhold even as the tests themselves have become ever more sensitive and accurate. Otherwise there would be no standard for comparing one result to the next, and an article about "undetectible" PSA written in 2005 would mean something totally different than one written in 2010.

That said, the treatment guidelines from AUCC specifically say that a doctor does not need to wait until aPSA is "detectable" as defined above, to begin salvage therapy. Doctors are expected to consider the individual facts and circumstances of each case, such as preop PSA and PSA kinetics, and all the pathology data, patient comorbidity status, etc. in deciding when to start salvage therapy.
Posted 1/31/2011 8:19 PM (GMT 0)

Mel,

The MSK nomograms are also known as the "Kattan nomogram", because they are based on the initial work done by Michael Kattan, PhD (statistician) and Peter Scardino, MD.  Scardino's practice out of Bayor University provided the inital data, but the database now includes widespread results from other institutions...as a result, there are enormous quantities of detaied information.

The information was transformed into a sophisticated mathematical model which is able, with considerable accuracy, to predict "lilelihood" of outcomes.  Statistical probabilities, as you certainly know, deal with large populations, not specific individiual results.

At the bottom of the MSK nomogram page, there are two links to published papers which describe the data and the results.  The first link is from the original publication of the nomogram results (published by Kattan, Scardino, Wheeler), and the second link is from the update, which includes Scardino's expanded work (he is now working at MSK), plus additional contributions from well-known doctors from elsewhere.

The Kattan, Scardino, Wheeler paper defines treatment failure by detectibale PSA this way:

"...the earliest date that the postoperative serum PSA level rose to 0.4 ng/mL or higher, confirmed by a second PSA measurement that was higher than the first by any amount..."

There are also other means of defining treatment failure in the paper, but they are not related to detectable PSA.

See the links at the bottom of the MSK page. 

The other thing to keep in mind is that patient micro-analysis of ultra-sensitive PSA test results is a relatively new phenomon which is pre-dated by the bulk of this nomogram work.

hope this helps...

Posted 1/31/2011 8:50 PM (GMT 0)
Casey:

Thanks for the info. I THINK the SRT nomograph was developed by Stephenson.

It seems that 0.40 as a failure theshhold is kind of high. I always thought the probabilities were very high (when I put in my data to predict the surgery outcomes). Perhaps that is due to this rather liberal threshhold?

Mel

Posted 1/31/2011 9:01 PM (GMT 0)

Mel,

Dr Anderw Stephenson from Cleveland Clinic is one of the doctors that contributed to the expanded Kattan nomogram work (along with several other well-known doctors from both MSK and CC).  Here's the author list:

Andrew J. Stephenson, Peter T. Scardino, James A. Eastham, Fernando J. Bianco, Jr, Zohar A. Dotan, Christopher J. DiBlasio, Alwyn Reuther, Eric A. Klein, and Michael W. Kattan

However, please note that the SRT nomogram specifically calls out the definition (for that nomogram) for Months Disease Free as the following:    Number of months after radical prostatectomy before PSA level was elevated to 0.2 or higher.    This is really obviously called-out on the MSK page, so maybe I don't understand your question...

Previously, I was speaking about the Post RP--Recurrence After Surgery nomogram...this is the one I thought you would be talking about first, before jumping to SRT success.  You haven't even had recurrence yet.

Understandable confusion...

edit:  clarification

Post Edited (Casey59) : 1/31/2011 2:10:44 PM (GMT-7)

Posted 1/31/2011 10:05 PM (GMT 0)
Casey:

We are talking about the same nomograph, the post RP one. I called it the SRT one but I meant that it gives the probability of SRT working.

If you look at THAT nomograph, it asks:

"Months Free of Cancer

Number of months without detectable cancer or a rising PSA following radical prostatectomy"
 
Again, what does that mean? If they are using the one decimal point assay (and I think they are), then my answer is roughly 12 months. A 2-decimal assay and my answer is 0.
 
Mel
Posted 1/31/2011 10:34 PM (GMT 0)
Repeating for clarity.

See the paper listed at the bottom of the nomogram "Post-Radical Prostatectomy (Recurrence After Surgery)"...which is the nomogram I originally answered your question about (your later reference to "SRT" threw me off on my 2nd reply).  There are two papers at the bottom of the web page, but both are related to THIS nomogram...not any other nomograms.

The Kattan, Scardino, Wheeler paper defines treatment failure by detectibale PSA this way:

"...the earliest date that the postoperative serum PSA level rose to 0.4 ng/mL or higher, confirmed by a second PSA measurement that was higher than the first by any amount..."

Read the paper for yourself...I think that the answer to your question has been provided in the text.

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