This next question comes from a daughter. Her father was diagnosed with stage 4 prostate cancer,
Gleason 9, back in February. He had 9 cycles of docetaxel, and
after the last month of chemotherapy, his PSA was 0.21. Is it safe, or what does it signify
One of the most important determinants of how people are going to do in the future is related
to what we call the PSA nadir. How low can you get the PSA? Oftentimes, people are looking at
how big a change it was—maybe the PSA was 500 to start with, now it's 0.2—that sounds spectacular.
It turns out that a PSA of 0.2 is signaling that there is still some cancer activity despite
all this chemotherapy and that small amount of residual cancer, then, can turn into a form of
chemotherapy-resistant cancer that can grow uninhibited going forward. The threshold
we're looking for is a PSA less than 0.1, so a PSA of 0.2 is pretty close; it's pretty good.
In some patients that may turn into a very long and extended remission, but unfortunately in some
others, it's a sign of well you didn't quite get to 0.1 and there are some resistant cancer cells
present; maybe we better be thinking about adding something else to try and get the
PSA all the way down to 0.1. What might that be? Well many of these patients are starting
with metastatic diseases, they've discussed, and there is research ongoing now looking at getting
these new PSMA PET scans to see if there are small pockets of residual activity, and we know
that with radiation treatment—SBRT, IMRT—that those residual spots could be sterilized.
So, this hasn't been established in a clinical trial yet, but there is thinking that you can
go ahead and get a scan at this juncture, find out if there are any residual hot spots,
and if there aren't too many, those can be safely radiated with minimal toxicity and maybe
we can get the PSA down to undetectable levels which is what we're aiming for.
Is it possible to have surgery after Tulsa-PRO in an event of relapse?
I'm not sure anyone knows, but Tulsa-PRO does cause an awful lot of scarring around the gland.
There are different degrees of Tulsa-PRO, which, it could be used for focal therapy,
and probably someone that had focal treatment would be a better candidate for a surgical removal
of the prostate if that was later necessary. I suspect that if the whole prostate is ablated
with Tulsa-PRO that trying to do any kind of an operation afterward would be almost impossible.
Are low-grade cancer cells originally found in the prostate biopsy capable of mutating
into more aggressive forms over time or do the
cells remain at whatever grade they do when they're first discovered?
It's usually the latter. The low-grade cancer cells—and this is why active
surveillance is so popular—tend to reliably stay low-grade cancer cells over many years.
Begs the question, then, why are we doing so much active surveillance? Why don't we just
release men to go on with their lives? Why do they need to have follow-up PSA testing with all this
energy and expense involved? And the answer is that as long as a man has a prostate,
prostate cancer is the most common cancer in men, and new cancers can show up. So, most of men that
go off active surveillance are not going off because the low-grade cancer cells have changed,
that's very unusual actually, either the problem is—one of two things—one is that
in the initial workup and diagnosis they missed a higher grade cancer that shows up down the line,
and that's more common in men that have random biopsies than the ones that
do regular MRI screening, or a new cancer just appears because that's the way prostate cancer is;
it's common and men can get a second cancer or third cancer people, I suppose,
subconsciously think that I've already had one cancer, I don't deserve another one,
but we see this in women that are being followed for breast cancers. They may have had a lumpectomy
or even a mastectomy, and that just doesn't buy them out of getting a new cancer on the other
breast, so they have to be screened for the rest of their lives even though they may only have one
breast, they still have to get mammograms every year to make sure they don't get another cancer.
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