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Interesting use of post-RP PSA nadir

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Posted 7/19/2009 6:56 PM (GMT 0)
I know we pooh-pooh the ultra-sensitive PSA test because its fluctuations are mostly meaningless. But I'm seeing some articles that point to a sort-of consensus that one use of those numbers may be approaching respectability.

Several studies have reached the conclusion that a post-RP nadir (lowest number reached) PSA of <0.01 is predictive of very low odds of recurrence. For example,

"Relapse rates in men with a PSA nadir of less than 0.01 (423), 0.01 (75), 0.02 (19) and 0.04 or greater ng/ml (28) were 4%, 12%, 16% and 89%, respectively. Men with a nadir of less than 0.01 ng/ml had a significantly lower relapse rate than men with a nadir of 0.01 (p <0.01), 0.02 (p <0.025) or 0.04 or greater ng/ml (p <0.01)." (J Urol. 2005 Mar;173(3):777-80.)

"Out of the 73 patients who have reached an undetectable nadir [<0.01], only 2 have failed (3%); this compares with 47 relapses out of the 61 patients (76%) who did not reach undetectable levels." (British Journal of Cancer (2000) 83, 1432–1436.)

"Based on the nadir PSA value, we divided 127 patients into three groups as follows: group A (n = 99): le0.01 ng/ml; group B (n = 16): 0.01-0.05 ng/ml, and group C (n = 12): ge0.05 ng/ml. ... During the observation period (median 31 months, range 6-75 months), biochemical recurrence occurred in 16 patients, that is, 1 in group A (6.3%), 4 in group B (25.0%), and 11 in group C (91.7%).... Conclusion: These findings suggest that the nadir serum PSA value measured by an ultrasensitive assay could be a useful predictor of biochemical recurrence after radical prostatectomy for clinically localized prostate cancer, and that careful follow-up should be considered in cases demonstrating a nadir PSA value >0.01 ng/ml because of the significantly higher probability of biochemical recurrence in such cases." (Urol Int 2006;76:227-231)

Yes, all are small studies. The results, as they say on Wall Street, are "interesting if true."
Posted 7/19/2009 10:15 PM (GMT 0)
Assuming no treatment is being proposed until levels reach, say, 0.2 ng/mL, then unless you are lucky enough to be in the group that is <0.01 ng/mL you might be better off, from a psychological perspective, having a result from a less sensitive test and only knowing it's <0.1 ng/mL. It could add to the worry and concern discovering that you are 0.04 ng/mL, for example.

Also, how was biochemical recurrence defined in these studies. Was it >0.1 ng/mL?

Roger
Posted 7/19/2009 10:35 PM (GMT 0)
PSA anixety is already hard enough on most of us, either pre-dx, or after treatment, feels like a knive over your head, hard not to think about it.
Posted 7/19/2009 10:52 PM (GMT 0)
London2000: the studies used different measures for recurrence. It's remarkable that, even with the differing standards, the studies (and there were others) came in so close together (3-6% for < 0.01 nadir) in their assessments.

Both: guys, I love you, but we differ. This is not a forum for philosophies, but forgive me this: I'd argue that 'tis better to know than not to know (and recall that you don't know half of my story). I know that my view is held by a small minority.

All the best to you both.
Posted 7/19/2009 10:53 PM (GMT 0)
Thank you for an interesting report. I think that as experience accumulates we will see more reliability from the high sensitivity tests.
Posted 7/20/2009 6:58 AM (GMT 0)
I understand the point you are making, CapnLarry, and I suspect that in a few years' time the use of the more sensitive tests will be so widespread that it will be unavoidable to not know your PSA concentrations down to the level of 0.01 ng/mL (or lower). Having that information will remove the surprise men get when they've had a series of <0.1 ng/mL results only to find, after a few years, they are suddenly above 0.1 ng/mL. They will not only have seen that coming but, from their nadir, will have been able to predict it from soon after surgery.

Knowing is good if your nadir is <0.01 ng/mL but much harder to cope with mentally if it isn't. Some men (and their partners) cope better with mental anxiety than others, but, as I say, I think the time will come when we all have to learn to cope. Doctors may need to learn how better to counsel men on the significance of their PSA levels, particularly if it's just a case of monitoring the PSA levels until a threshold is reached for medical intervention.

From a scientific point of view, the findings from these three investigations make sense. You would expect a correlation between the level of the nadir and the likelihood of recurrence. All the same, in science every theory has to be tested so it's right that this work is being done and reported.

Also, since there is such a good correlation between levels and the chance of recurrence, this suggests that there is already good reliability with the high sensitivity tests. But, as I said in another post, these methods have be thoroughly tested before being put into use.

Thanks for posting some interesting information, CapnLarry.

All the best, Roger
Posted 7/20/2009 12:09 PM (GMT 0)
Hi guys,
Sorta makes me wonder what my ultra sensative test would have been. The mindset in my Docs setting is that you would not start anything until it reaches 0.1 or 3 consecutive rises, which I had both, and sometimes it will go up a little and never go any higher. Not to mention any worry it would cause if it did blip up and down. Mine is back down to <0.04, as low as his assays read, so here we are again! For myself I will continue with the one I am on now because I don't need the worry factor. Very good post.

David
Posted 7/20/2009 3:26 PM (GMT 0)
CapnLarry
Thanks for the great information. We still don't know if the ultra sensitive tests will have true predictive ability but this tells us not to completely dismiss them.

The issue of how much a patient really wants to know has got to be a tough one for doctors. I t may be that with some doctors, you need to ask questions to show that you want to know. I am one of those who wants to know everything -- even when my urologist is uncertain and I feel he respects this in our consultations.
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