0.03 ng/ml best indicator of biochemical recurrence (Johns Hopkins)

Craig10-
Why do your uPSAs have different lower limits - <.01 on 2/14 and <.02 on 6/14? If they were done at the same lab the undetectable limit ought to be the same. Then you were switched to a conventional PSA test?

Yes, the JH study is only about a first uPSA. The Koulikov study or UCLA study of men with T2 could potentially be more relevant to you. Your numbers look very good so far.

- Allen

Gemlin,

BCR after surgery is used a surrogate for clinical recurrence because it is a very good early indicator. If you wait until it progresses to the point of being clinically detectable, you risk sacrificing survival, as shown in 3 RCTs now.

- Allen

However, I do still find confusion when looking back one more time and see this, which I did not even notive at first:

Somebody said...
Among men whose first uPSA was ≥ 0.01 ng/ml, about half eventually had BCR.
57 percent were BCR-free at 5 years; 49 percent at 11 years.
Mean BCR-free survival: 10 years.........................................................................................
Among men whose first uPSA was < 0.03 ng/ml, 85 percent remained BCR-free.
91 percent were BCR-free at 5 years; 84 percent at 11 years.
Mean BCR-free survival: 15 years

I hesitate to point this out as I am likely to get flamed or at at least be reminded (probably deservedly) that I probably should not even look at stuff like this, because it is all over my head. So apologies in advance.

But isn't .02 (or even .01) greater than or equal to .01? So a .02 would be in that 1st group, whose first uPSA was ≥ 0.01 where about 1/2 would have BCR?

But, isn't .02 also less than .03? So wouldn't .02 also be in that last group whose first uPSA was < 0.03, where 85+% remained BCR free?

Again, I hesitate to point this out, because I am certain I am missing something, my eyes are crossing trying to see it. In fact I am embarrassed for myself in advance. But someone help a slow brother out and point me to what I am missing please. I'm sure I am looking at something and not seeing it. Would a .02 be in the group with 1/2 have BCR, or the group where 15% have BCR?

Tall Allen said...
I suggest you revisit it in a few days - sometimes the math takes a while to sink it.

Good idea!

Allen!

Thanks for getting back to me-- all of this is interesting ton say the very least.....To answer your questions of me...

1. Bottom line--- I have bounced around to a few labs.

2. The results below in my signature are my results and reflect what my psa was at those times and of course probably some variability in assay? Instrumentation?

After my last test I complained a bit to my uro--- "hey, doood, I said, why the heck do I not have the sensitive test anymore"? he replied...."well, the lab used a different test, but don't worry about it-- you're fine.....I wouldn't start any treatment anyway if you did run into trouble until 0.1 anyway"...... at least I think that's what he said.

I really didn't call him Dude. What do you think about his position?

halbert said...

jpenn44 said...
Forgive my ignorance but is their a standard deviation with PSA testing equipment?

jpenn, yes there is, and you'll have to ask the specific lab what machine they use and what it's limit of precision is.

Unfortunately, there is not a single "standard" instrument that runs on a standard protocol. The same question keeps rolling around in my head, and the answer all comes down to "it depends". Being an analytical chemist, the fundamental lack of that bit of information bugs me.

I would suspect that a method that is capable of reporting a value of <0.01 has a limit of precision of something like +/- 0.005.

As you, my analytical brain has trouble comprehending how there cannot be a standard testing protocol for something as important as something that is being measured to this level.

How can you validate the .03 number when the deviation on the machine might mean the number is actually .02?

Just as we have a gold standard in reading biopsies, why is there not a true machine standard for reporting PSA? Why isn't there standard machines, testing protocols or even regional centers that only report PSA?

I apologize as this is a bit of a tangent from the intended conversation on this thread, it's just the lack of controls when dealing with these types of numbers baffle me.

jpenn, the upside is that technology is advancing, and new equipment is coming on line and going down in price, so more and more labs will have the current 'best'.

The Uro I go to in this small town has an instrument in the office that reports down to <0.04. The local hospital testing lab goes to <0.1. I have no idea where I'd have to go to get the <0.01 test.

I'm glad someone else in here understands what I'm talking about. In analytical chemistry, the absolute correct way to report any value is to include the +/- of the precision limit. Average joe doesn't even understand the difference between precision and accuracy.

Tall Allen said...
As I replied in a previous post on this thread, "Johns Hopkins used the Hybritech PSA, Beckman Coulter Access 2 assay... the Hybritech Assay coefficient of variation (precision) is ±5%, and is most often used in the US."

So, if this instrument is being used, a .02 would be: 0.02 +/- .001, which is pretty darned good.

Interesting stuff, Allen, and thanks for the link to your commentary on the Sokolov study.

I think the biggest impact of this information for me is to confirm my well-placed confidence in my Urologist (and my MO and RO) that he is on top of the developments in the arena of PCa. With my post-op pathology, he and I had a very lengthy discussion about ART (of which he was a proponent) after surgery/healing time. He acquiesced to my desire to forgo ART, and monitor closely with uPSA testing. After three small, but subsequent rises in uPSA to .07, we pulled the trigger on SRT. Only time will tell what road lies ahead, but I'm happy that I have a great medical team to partner up with on whatever happens next.

Thanks again!

Rich

Gemlin- I did not say anything remotely like that uPSA is a good single source indicator for the decision to undergo SRT. What I said was that it is a good indicator of biochemical recurrence.

Sheepguy - you pass the math quiz - .02 is exactly halfway between .01 and .03. Congratulations.

So the value of .02 by virtue of being smack dab in the middle puts him in both risk categories?