But it brings up the idea that someone's been treated by PET -- or cryo I mean, I'm sorry, cryo
or HI-FU and their their PSA's been stable, and now it's rising, and this brings up the concept of
when people are going to start using it. They see this rising PSA, they see doubling times,
and it's often quoted from your institution, "Now, if you're between 0.2 and 0.5 there's this
percentage chance it could pick it up; if you're 0.5 to 1 there's this percentage chance, and if
there's one to two, it's even higher" and so in my mind and in people's mind they're thinking,
well I want to go right as early as possible, when there's a 0.2 or 0.3, and other people
are thinking why don't I just wait till the PSA gets back up to one so it would be most
accurate at a higher PSA level? See this is what dogged us during the choline times -- we'd say,
"oh just wait around your PSA gets to one or two, and then we can find this" and people say,
"I don't want to wait that long," so how do you figure that out in your head where
people are advertising, "look with the PSMA PET we can get you potentially we can find
it at 0.2," but yet it becomes more accurate as the PSA gets higher?
So accurate... It's probably equally as accurate at all stages. The patient level detection rate
goes up, right? So as your PSA rises you have more disease, right? So it's easier to visualize.
I don't think anyone should ever wait for disease to grow so that we can see it depending on the
patient. So if you're a patient who's had a radical prostatectomy back in 1999 and your PSA
became 0.1 in 2015 and now it's 0.2, wait as long as you want, right? Like, I mean that that patient
has a very slow PSA doubling time, you know, maybe you will never even have issues with prostate
cancer even if you never get treatment. Whereas, if you had a radical prostatectomy, your post-op
your PSA is 0.3, you know, six to eight weeks out, and then your PSA is 0.5, you know, four
weeks later, get a PSMA PET right then, right? Because you're not going to put off anything,
you should be getting lined up for salvage radiotherapy because we know it's effective,
even blind salvage radiotherapy is effective, right? Without having anything to aim at. So it
really depends on that individual patient and when you're making a decision of what you want to do,
and that's that's why I actually would never make a guideline that says always get a PSMA PET at 0.2
because 0.2 means different things with different patients. If you're deciding to enact a treatment
plan maybe at that time is when you wanna get your PSMA PET, but you know, there's a lot of
data and I, you know, Mack [Roach, MD] could do a much better presentation on earlier radiation
therapy and how that has better outcomes. I would prefer not to have patients wait for them to see
disease because you're waiting for your disease to grow seems like not a good idea, and then what
if you're one you're the--you know--the 10 or 15 percent where we don't see disease at that time,
you know, it seems like a bad choice. And the other thing I would add to that is a PSA 0.2
means different things in a different way -- after radical prostatectomy, you have disease, right?
After radiation therapy that might be residual, you know, burnt out prostate; after cryo,
god you probably never get down to 0.2, right? So, you know,
really you have to take into account the individual patient factors and,
you know, as a as an imager I should never be telling uh Mack or, you know, Peter Carroll or
Matt Cooperberg what they should be doing, you know? They're going to talk to the patients,
they're going to know the patient's risk factors, they're going to know their genomic
risk factors and everything, and determine when the right time is to get a PSMA PET.
But part of the appeal is "lower is better," so you can get it at lower and lower PSA values
which is attractive, right? But you're going to have a number of people that are negative that
they're going to ask, "what do I do now?" You work with your physician and possibly
come back and get another one. You must have plenty of people that have had one,
nothing; two, maybe they found something, or they're up to their third one, right?
Yeah, so I would just say that like, let's say you've had a radical prostatectomy and
your PSA is 0.2 and the PSMA PET is negative, you should get salvage radiation therapy,
right? The key is that you don't have disease outside. The places where PSMA
PET changes management is when you have disease outside of the normal radiation therapy fields.
You should not withhold therapy that has good potentially curative intent,
you know, at low PSAs because your PSMA PET is negative, and that -- like there's a lot
of data out of Australia now where they've done a ton of PSMA PET and a lot of patients who had
negative PSMAs ended up observing and they all recur, right? But you could have gotten salvage
radiation therapy which is the standard treatment before PSMA PET and potentially not recurred for
a long time, right? And so I think you have to be really careful, and again this is where I
don't get outside of my wheelhouse of telling people how to manage their disease, but you know,
really listen to your radiation oncologists and your urologists, your medical oncologists
because, you know, I showed that 50% of patients have their management changed with PSMA PET,
that doesn't mean that the management changes are right, right?
Right.
We have to learn how to use it and we really need to be careful about how to
incorporate this into our decision making process.
Yeah, well said, well said.