Ultrasensitive PSA test that is more precise than <0.05?

Hi All, Hope this isn't a rookie question but I couldn't find an answer in the old posts.

My question is whether I should ask for a more precise PSA test than undetectable <0.05. My MO at Stanford said this is their standard ultra sensitive test and I should continue tests at their lab.

Still, I often see references to scores between 0.05 and 0.01 hence I'm wondering where I am on the spectrum. A more precise score probably wouldn't change my immediate treatment plans (EBRT + 12-18 months of ADT+Zytiga), but I've seen studies that show better odds based on nadir (and scores <0.05 so I assume a <0.01 is better than a <0.05.

Thanks in advance for any insights.

FWIW, MSKCC also uses <.05 as the undetectable limit. I believe that it’s because they believe anything lower doesn’t mean much in the context of recurrence .

Andrew, he started with surgery, which failed, then added ADT and SRT. Thus the nadir plus 2 isn’t germane.

Duane, the level of testing you are on is fine. I know you are still treating for a cure. Expect your PSA to be undetectable (regardless of regular, sensitive or ultra sensitive) while on ADT. That shows the ADT is working. The challenge will be when you come off of ADT.

IMO, you're fine. Yes, there are some docs (a relative few), who want to call out BCR at 0.03. Most, however, subscribe to the general concept of "2 or 3 successive rises above the detection limit"--so whatever the detection limit is, the wait for that line to be crossed, then wait a bit for a re-test, then another time after that.

The idea is to eliminate noise. And, the lower the detection limit, the more likely noise is going to be. And, as we've seen in here, noise drives some guys nuts. My current lab (Labcorp) runs a detection limit of 0.006. Previously, where I lived, the best they had was 0.04. Yes, it appears that now I'm "more undetectable", but I also know that if it starts to move, I probably won't do anything until it gets somewhere close to 0.1 anyway.

And, here is where I put on my analytical chemist hat, and point out that the OP is asking about precision, where he really means detection limit. And now I'll take that hat back off and spare the lecture about limits of precision, relative accuracy, detection limits, and other statistical functions relative to chemical analysis.

IMNSHO
You are fine, as treatment won't restart/start until PSA reaches a much higher level.

For the first two years I was being tested where undetectable was <0.1 ,
then I asked for a greater sensitivity and I immediately saw my PSA hovering just below 0.1 at 0.08.
Made my life more stressful.
No new treatment, just watch the ball bounce incessantly.

All - Many thanks for the insightful perspective. All of it is very helpful and I'm most grateful.

As we all know, it's no easy feat to learn everything useful about this disease. Will take this all on-board and keep you all posted.

In the meantime, remaining grateful for the <0.05. Also, working to find the right balance of a) not overlooking important info for my treatment with b) leading my life and not thinking about PCa all the time.

How do you know your not <0.01....you are <0.05....if 0.05 is your labs limit then you could also be <0.01.

I have always been <0.03....that is as low as my lab goes..

Why? What would be the point or use? Never been into ultra sensitive testing, all I have ever seen it do here, is to create or increase PSA anxiety, and in most cases, has no real use even with future treatment (if needed).