So, now we're going to go into the what I call general radiation questions that
we get inundated with and it's important to address those the rest of the way. So,
my favorite one is, if someone gets surgery, right? They are told the best PSA
is an undetectable PSA after surgery, right? Just flat-out — I mean of course not zero,
but they use ultra-sensitive tests. So now, if I threw that question back at someone who
has such a history of radiation therapy and treatment to you, and someone's coming to you
and they've been treated or they're about to be treated, what are we looking for in terms
of a PSA response? Do you expect your patients to go extremely low, to go to zero after six
months? I mean what's the expectation when it comes to specifically PSA and radiation?
Well it's a whole lot easier to do surgery and
then follow the PSA and if it stays low, you're good.
Right.
That's not the way it is with radiation therapy. With radiation therapy we don't kill all the
prostate or remove all the prostate tissue, so it continues to make PSA, and there are many
different patterns, in part depending on the kind of cancer you have, the biology of that cancer,
the kind of radiation that you received, and so forth. As I showed in one of the slides, at
least 50% of the patients who have HDR monotherapy will drop down significantly their PSA from, say,
eight down to two or one, and then it might hover there for a while and within the first five years,
it's not uncommon that it goes back up to one degree or another, sometimes rather dramatically,
and I spend a fair amount of my time explaining to patients that doesn't mean failure and
given our track record, the vast majority of patients those rises will represent a bounce,
but it is a trying time for patients and doctors alike when you have to start interpreting. What
you don't want to do is go in too fast and go in and biopsy or make the assumption that
the patient has recurrent disease when in all likelihood they don't. If you're starting with
a patient with high-risk disease, starting out with a PSA of 50, T3, and so on and so forth,
and they come back a year later and their PSA is rising, you better start worrying. If they
had an intermediate-risk group and you had a PSA that started rising, in all likelihood,
that's a bounce. So it's a challenge; there's no easy answer. Things like PSMA scans are
becoming helpful in making those kinds of determinations in patients who have no prostate,
residual prostate. You can use a very low number like 0.2 and do your PSMA scan, but when you have
an intact prostate there's going to be some background, so the number has to be higher,
more like two in order to do your PSMA tests to evaluate for evidence of recurrence.
So is it fair to say that if you still have a prostate—this being the symbol of a prostate in
my house—if you still have a prostate. I know, but as we get older, God plays a horrible joke,
our prostates get bigger, right? But our prostates get bigger. So, if you have a prostate still in
there and you're getting radiation, is it safe to say that everybody has their own individual
low number in terms of a PSA response and you're just kind of monitoring a range to
see if you're comfortable with. he treatment outcome, right? So, people aren't — people
shouldn't have the expectation to go to 0.1 or 0.09. It's — you're going down to a lower number
and you're staying at that number and a range of that number years and years later, correct?
Yeah, originally when I started doing this, the — one of the criteria was you had to be 0.2 or
less after a radiation therapy, and I don't think that's a valid conclusion at this point. I like
to see patients go less than one, makes me feel comfortable, and if they stay in the you know 1,
1 and 1/2 range, I'm feeling pretty good about them, but remember, within 5 years half the guys
are going to be going up, and it takes, in fact, in one study we did two and a half years for the
PSA to even nadir, so it's gonna go down and it can bounce more than once and it can go
up and down. You have to work closely with your experienced brachytherapy radiation physician and
your urologist to make sure there's a coordination going on there so we're not treating the patient
unnecessarily or doing biopsies that maybe might be not needed or potentially harmful.
Did you say two and a half years? You said two and a half years to go to that point?
To the final nadir.
Wow.
Not to be surprised, it can be a long time. Now, typically, the PSAs drop by about 50% within 3
months, but not all the time, and if they don't, I don't get too worried about it. I can't recall
one where it went up above the baseline when you check PSAs just before we do treatment,
but even then I wouldn't get too excited about it. I would just repeat the PSA in a few months.
But these bounces that you discuss, the bounce,
is it an undulation? is it a series of bounces or is it generally — are you saying bounce,
singular, that some people can expect after radiation that doesn't necessarily mean it's
cancer coming back, it's just an effect of inflammation or something else there?
It's both I don't understand the mechanism completely. There are
patients who bounce just once and there are patients who bounce multiple times.
Wow.
Yeah, so you have to — and again the typical bounce is in the 1 to 2, 3
range. I have had patients at 10. I had one guy at 16 and didn't treat them.
They didn't want to go with treatment and waited, and their PSA went away.
And how does — okay, so I don't know if there's anything else to cover on the PSA.
Well, let me interject that PSA rises after five years are considerably more worrisome
for recurrent disease than when it happens in the first five years.
Okay.
We know very well ten years is, you know, not even necessarily a hundred percent safe territory.