Nanoparticle PSA Test

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SHU93
Regular Member


Date Joined Aug 2008
Total Posts : 328
   Posted 6/9/2010 7:41 AM (GMT -6)   
Saw this news yesterday. Has anyone had this test done?
 
My other question is for those who have the current ultrasenstative test is there is any reading of PSA means at some point reoccurrence will occur? Because from what I understand this new test is just an even more sensitive test to see if you have any PSA in your blood and their basing a level on the PSA of whether prostate cancer is still in your body?
 

Nanoparticle PSA Test Predicts If Prostate Cancer Will Return; Ultrasensitive Test Gives First Accurate Answer After Surgery

 
 
Age Dx 37, 7/2008, First PSA : 4.17 5/2008
Second PSA After 2 weeks of antibiotics : 3.9 6/2008
DRE: Negative 5/2008, Biopsy: 6 out 12 Postive all on right side, Gleason 7 (3+4). Bone Scan/CAT Scan: Clear 7/2008
Cystoscope: Normal 7/2008, Prostate MRI: Normal 7/2008
Da Vinci Surgery 7/2008, PostOp: T2c (On Both sides), margins clear, seminal clear, nodes, clear. Gleason 6(3+3).
6 Post OP PSA's from 9/2008 to 6/2010: <0.1
 
 
 


142
Forum Moderator


Date Joined Jan 2010
Total Posts : 7082
   Posted 6/9/2010 8:36 AM (GMT -6)   
Looks like you have to be in a study to get this test done for now.

Casey59
Veteran Member


Date Joined Sep 2009
Total Posts : 3172
   Posted 6/9/2010 10:31 AM (GMT -6)   

The development of this test has been in the “news” for some months.  Here’s a link to an article from last year talking about this same test.  It is generally new, and it does have a lower limit than the existing ultra-sensitive tests, but the practical commercial application is still being viewed with skepticism.  As usual with the media/news releases, the headline (while eye-catching) overstates the apparent incremental benefit. 

Here’s the bottom line

Today’s most sensitive PSA assays (the DPC Immulite sensitive assay) has an analytical detection limit of about 0.002 ng/mL, functional sensitivity of about 0.005 ng/mL and a clinical useful sensitivity of about 0.01 ng/mL.  Medical studies demonstrate how ubiquitous and non-specific PSA really is at concentrations below 0.1 ng/mL. 

Those of us familiar with the PSA test know very well what PSA specificity means in the context of before treatments…it means that both cancerous and non-cancerous (BPH, infection, recent DRE, bike riding, etc) factors can release abnormally high levels of PSA into the bloodstream. 

After surgery, the PSA test also lacks specificity at levels below 0.1 ng/mL because (again) both cancerous and non-cancerous factors can release PSA into the bloodstream in measureable amounts.  In addition to the non-specificity, the inherent, naturally occurring variation in PSA (day-to-day, test-to-test) in the blood is now—with the ultrasensitive PSA tests—greater than the measurement detection limits.  Studies have shown that the coefficient of variation (CV) based only on daily variation of PSA is between 10% and 20%.  The phrase “PSA Anxiety” has taken on several meanings over time, but the original meeting was for exactly this situation (see this article on “PSA Anxiety—The Downside of Ultra-Sensitive Tests”; click on the link, then scroll down to the yellow box at the bottom).

That being said, and with the recognition of “PSA Anxiety” as a very real factor, there is a place for the ultrasensitive PSA test to be used intelligently in monitoring the post-RP patient.  The largest group of patients being operated on today have low pre-surgery PSA and low Gleason scores, and after surgery have no EPE and negative margins.  Today, these men are commonly prescribed the “standard” PSA test because they have low likelihood of recurrence.

On the other hand, men with any of the factors listed above (high pre-surgery PSA, or intermediate or high Gleason scores, or EPE or positive margins) are excellent candidates for the existing ultrasensitive PSA test.  BUT, given the functional coefficient of variation of the non-specific post-surgery PSA levels, there doesn’t appear to be any additional value to push detection limits lower than currently commercially available.

Maybe there is another clinical use of the newest nanoparticle-based assay that will one day become beneficial outside of the research lab…



Rolerbe
Regular Member


Date Joined Dec 2008
Total Posts : 235
   Posted 6/9/2010 10:39 AM (GMT -6)   
Nice recap Casey. I guess the real thing to be hoped for from the ultrasensitive test is that it somehow give us a differential test between fast and slow growers. If we had that, then there would be a viable justification for all the recent talk about overtreatment and overtesting. Right now that talk is criminal if you ask me -- there is no doubt about overtreatment today, but without a high sensitivity and specificity test for fast versus slow, watchful waiting seems like russian roulette.
51 YO
PSA at Dx: 8.2
DaVinci RALP: 10/31/08 -- Great MD in New Haven, CT
Negative margins, no extra-capsular involvement
One nerve spared
PSA at 0 for just over a year now.
 
 


Casey59
Veteran Member


Date Joined Sep 2009
Total Posts : 3172
   Posted 6/9/2010 10:50 AM (GMT -6)   
Rolerbe said...
Nice recap Casey. I guess the real thing to be hoped for from the ultrasensitive test is that it somehow give us a differential test between fast and slow growers...
 
That would be a different test...you won't get that from this nanoparticle-based PSA test.
 
Frankly I wish they had spent the scarce research resources focused in the area you describe instead of a more-sensitive ultra-sensitive test.  A much stronger need exists there.  I'm sure it's being worked on...we just need a shout of "Eureka!" from those guys.

SHU93
Regular Member


Date Joined Aug 2008
Total Posts : 328
   Posted 6/9/2010 11:10 AM (GMT -6)   
Thanks for info!
Age Dx 37, 7/2008, First PSA : 4.17 5/2008
Second PSA After 2 weeks of antibiotics : 3.9 6/2008
DRE: Negative 5/2008, Biopsy: 6 out 12 Postive all on right side, Gleason 7 (3+4). Bone Scan/CAT Scan: Clear 7/2008
Cystoscope: Normal 7/2008, Prostate MRI: Normal 7/2008
Da Vinci Surgery 7/2008, PostOp: T2c (On Both sides), margins clear, seminal clear, nodes, clear. Gleason 6(3+3).
6 Post OP PSA's from 9/2008 to 6/2010: <0.1
 
 
 


Casey59
Veteran Member


Date Joined Sep 2009
Total Posts : 3172
   Posted 6/11/2010 9:36 AM (GMT -6)   

Rolerbe said...
Nice recap Casey. I guess the real thing to be hoped for from the ultrasensitive test is that it somehow give us a differential test between fast and slow growers...

Casey59 said...
Frankly I wish they had spent the scarce research resources focused in the area you describe instead of a more-sensitive ultra-sensitive test.  A much stronger need exists there.  I'm sure it's being worked on...we just need a shout of "Eureka!" from those guys.
 

There was somewhat of a "Eureka!" published today in UroToday.com by Dr. William Catalona (who was also involved with the Nanoparticle PSA test, which was the original topic of this thread) and Dr. Brian Le in a paper titled:  "[-2]Proenzyme prostate specific antigen [a.k.a. “p2PSA”] is more accurate than total and free prostate specific antigen in differentiating prostate cancer from benign disease in a prospective prostate cancer screening study."  A step in the right direction…!

The research group identified a specific niche that this test could fill…patients with a total PSA between 2 and 4 ng/mL, which is a group of particular diagnostic uncertainty.  The p2PSA test has improved sensitivity and specificity for aggressive PC in this group.

It’s not a silver bullet (don't expect one), but it could be a baby-step improvement in clinical diagnostic capabilities to better under understand the clinical biology of one’s PC, especially for (but not limited to) those choosing AS.

Link to article.

 
 
 

Post Edited (Casey59) : 6/11/2010 9:28:17 AM (GMT-6)

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