Is a PSA of 0.023 considered undetectable? This person has not had surgery. They've been
on Zytiga and Firmagon for quite a long time. They get a shot every month and they're kind
of wondering, do I need to do something further, or is this a good spot?
Yeah, the word undetectable and the clinical relevance of having a low PSA are not precisely
the same thing. Sometimes, people use the word undetectable for a surrogate for saying
the PSA is low enough, we've arrived; we're in a good place. I would say that a PSA below
0.1, you've arrived at a good place. The PSA is low as a result of a treatment. There may
not be evidence that going lower and lower—you can measure down to 0.01 or sometimes 0.001—is
going to translate into long-term better outcome than the person that just gets below 0.1.
So, someones, people say it's less than 0.1, it's undetectable—well, on certain assays,
it may not be undetectable because that means on the assay they couldn't detect any PSA
using that methodology. So, undetectable is always signaled by the chevron sign, the less
than sign, in front of the number. That means that as low as that assay could measure, they
couldn't find any PSA at that level. I think they said 0.023, so there was no chevron sign,
so it wasn't technically undetectable, but it's certainly in a very good range, less
than 0.1. They appear to have an excellent response to hormone therapy and trying to
get it lower would not in all likelihood translate into some better outcome someday. They've
arrived.
So, that same patient is wondering if they can go on testosterone therapy. They want
to get it replaced, and obviously the side effects of hormone therapy are quite extensive
when it comes to fatigue and losing muscle mass. I understand why they'd want to go on.
Is this a safe area for them to go into or are there certain things that they should
look out for in the process?
Yeah, it is safe. We don't know too much about this person's case; did they have metastatic
disease on scans before? Are they newly diagnosed? Do they need to get radiation and be cured?
So, we don't really know the background, but in the old days, even newly diagnosed patients,
we would treat with intermittent—so-called—intermittent therapy. These days, because radiation has
become far more tolerable, we usually say let's just try and cure it rather than doing
intermittent therapy. In people that have metastatic disease that want to take a holiday,
studies are really clear that you can safely take a holiday. You mentioned taking testosterone
— just stopping the Zytiga and I think it was Lupron they mentioned as well, that should
result in the patient making their own testosterone. They don't have to necessarily take testosterone,
although there may be a delay. But some men, some elderly men, you stop their Lupron and
their testosterone doesn't recover, and the question arises, can we safely give those
men testosterone? And I would argue that yes, that we certainly can. It's essentially what
we're doing when we stop Lupron. The testosterone that comes from the man's testicles is the
exact same chemical makeup of any testosterone that you would apply with a cream or a shot,
and I don't see any difference whatsoever. PSA has to be monitored; blood counts have
to be monitored for it all to be done safely, and then at some certain threshold that the
doctor may specify—PSA rises up to where it was before or to 5.0 or to 10.0, some level,
then the Lupron and Zytiga will need to be restarted with the expectation that the PSA
will go back to undetectable levels.
Now, with the testosterone coming back into the man's body, how long does that take, and
does it depend on whether it's a second-generation or third-generation hormone therapy?
So, it's age-related and treatment duration-related. So, the older the man is and the longer they've
been on treatment, the slower the testosterone recovers, as a general rule. Now, you're probably
referring to this new medication, an oral Lupron called Orgovyx, which is an attractive
alternative to Lupron because the testosterone recovery rates seem to be much more predictable
when you stop it. The formula I already cited of older and longer-term treatment resulting
in longer delays in getting your testosterone back, reportedly, is not the same for Orgovyx,
that the recovery of testosterone is much more predictable. So, I haven't had enough
first-hand experience with Orgovyx to see that in action, but that's what they're reporting
from the clinical trials that were done.
So, we have a 72-year old; he has a Gleason 8 prostate cancer. He had IMRT and he has
been on hormone therapy and his PSA is about 0.28, and so he's wondering should he get
a PSMA scan? Is his PSA, you know, again, it goes back to that, "Is it undetectable
or is it just in a good state?" And so he's wondering what the next steps are?
It would be interesting to know how long ago he started hormone treatment. We have talked
about the fact that your PSA, ideally, will go down to less than 0.1. This individual
hasn't quite arrived at that threshold, but we didn't mention that it takes, on average,
anywhere from 4-6 months for the PSA to float down to that level. If this is early on in
the patient's treatment course, I would just wait a few more months and expect that the
PSA will ultimately get below 0.1. If it doesn't, that's called a high PSA nadir, and in studies
done with radiation and without radiation, that's an indicator of problems, that if you
can't completely snuff out all the PSA production, it speaks of some cancer cells in the body
that are able to continue functioning even in the absence of testosterone. That's not
good news because in the prostate cancer world, one of the reasons that we're so optimistic
that people are going to do well with prostate cancer is that you always have the hormone
blockade safety net that can put people in remission for 10-15 years, easily, and if
that is not going to be the case for this specific individual, this is a real problem.
So, we don't have enough information in this situation. It may be that he has only been
on hormone treatment for 2-3 months and a PSA of 0.2 would be perfectly fine, but if
he has been on it for 6-8 months and the PSA is still above 0.1, then it starts to raise
the question of whether there's a more serious variant of prostate cancer here that would
require more aggressive treatment.
So, in that case, would you suggest a PSMA scan to check and see if it's anywhere else
in the body, or would you automatically put him on a systemic treatment that's a different
level of hormone therapy? Yeah, I think it would be logical to do a PSMA PET scan. You
can pretty much say it would be logical to do a PSMA PET scan in almost all situations
now. In the old days, we would do CAT scans and bone scans, and MRIs, and look — supposedly
looking for where the cancer is, but the PSMA PET scans are so dramatically more accurate
and sensitive that anytime a problem is arising, unless the PSA is completely undetectable,
the PSMA PET scan is going to be kind of the first reflex go to action that is going to
be implemented on a routine basis going forward. It's nice to know that they're being commercialized
as we speak; that Medicare is now paying for PSMA PET scans, and I expect that the Blue
Cross Blue Shield PPO insurances will be following soon.
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