So, does the PI-RADS score have anything to do with staging prostate cancer or does
it really just show us whether or not we should get a biopsy?
Well, initially it's been used to decide who does need a biopsy and just for clarity the PI-RADS
system is a numbering system from one to five; the higher numbers indicate a greater likelihood that
the spot that they're seeing in the prostate with the MRI is something that is above a Gleason 6
and that would be considered actionable prostate cancer. There are studies that
have looked at people on active surveillance who have visible lesions with the PI-RADS system and
shown that the likelihood of going off of active surveillance—because of a higher Gleason score
discovered later—is greater in people that have visible lesions and in people that have higher
scores on the lesions that are seen—higher PI-RADS scores. So, it does have some predictive power.
There's also some suggestion that people with higher PI-RADS scores have higher relapse rates
after surgery and radiation, and or radiation and the PI-RADS system, the MRIs methodology for
detecting these lesions is useful for detecting someone who has a higher risk type of cancer
and this does seem to be independent from the biopsies, and how high the PSA is,
and the other factors that we've used to try and predict the future. So, it's not something that
I rely upon heavily because I don't think that the degree of the power of the information is that
great. So, you can in large studies you can show that there's predictive power with these PI-RADS
lesions and that having a PI-RADS five will place you a little higher risk of disease progression
someday compared to, say, a PI-RADs 4 or in a situation where people don't see anything at all,
but I think that the likelihood that it's going to change the selection of therapy, in other words,
you'll start managing someone more aggressively because of this information? No, I think it's
more theoretical and not— I'm not using it, practically speaking, in my day-to-day practice.
So, the main information, then, that you're using would be Gleason and PSA, right?
Yeah, it's— I mean, when you're talking— it's different roles in different situations
but that's correct. So, if you're trying to decide what to do for a newly diagnosed patient
should they have radiation or should they go on active surveillance? Yes, we rely on the Gleason
score, and how high the PSA is, and how many core biopsies are positive if they had a random biopsy;
MRIs are useful for detecting disease in seminal vesicles or occasionally even in lymph nodes,
and of course, that drives the decision-making process, but we're not using the PI-RADS system
to decide who should get more or less aggressive cancer treatment.
Thank you for clarifying that. I know when it comes to staging there's a lot of confusion.
I think people are trying to figure out what to do, and we've actually created a tool for
that if you would like more information about staging and the treatments available to you can
go ahead and answer our quiz, and basically, you answer six questions and it'll tell you what stage
you are and the treatments available to you. You can go and click that on the link below.
So, how useful would you say 3T MRI is for figuring out if there's cancer in the pelvic
nodes? Would you go ahead and go straight to a PSMA since that was recently approved?
This person is trying to avoid radiation altogether and I think they're concerned
if there is pelvic node involvement that they'll go ahead and need to do that.
Well, until PSMA came along, we were using Axumin PET scans, although they weren't always covered
for people that were newly diagnosed; they were used more to detect lymph node disease
in people that were relapsing after surgery or radiation, but the accuracy of MRI and CT
to detect lymph nodes in the pelvis is probably comparable, and MRI and CT use a size criteria.
If the lymph node gets really chubby and lumpy and big—they say if it's over a half-inch across—then
they start thinking, "Wow, that's just too big for a lymph node; must be cancer." The criteria
for detecting cancer in the lymph nodes is pretty crude if you use MRI or CT. It's, of course,
scans were done routinely because if you do have a big lump of cancer, you do want to know about it,
but all the precautions that have been taken through the years to
handle the possibility that there's cancer out there that's not being seen on MRIs and
CTs has, you know, built up this whole high-risk, intermediate-risk categories,
and all that is talking about the risk of spread, and of course, the most common site
of spread is the lymph nodes, so yeah, they've been pretty unsatisfying through the years.
If someone has a clear scan with an MRI or CT it does not mean there's no cancer in the lymph nodes
and that's been well understood for a long time. As you point out, the PSMA PET scans and to some
degree Axumin pet scans are a whole new world and how we're going to incorporate that into our
management of people with higher Gleason scores is still undecided. People that have clear scans,
can they avoid all the radiation and maybe the hormone therapy? Studies have yet to be
conclusively performed in that regard, but it sure seems to make a lot of sense.
So, now that PSMA is approved and covered by insurance for the most part, do we see Axumin—
how do we place that? When would that be used in the process of diagnosis? Would that be the first
go-to and then a PSMA? So, Axumin PET scans aren't as accurate as PSMA PET scans at low PSA levels,
which is say, less than one or two, and PSMA really outshines Axumin PET scans at that level.
As the PSA starts going higher, all scans start working better; Axumin works better,
even CTs and MRIs start working better because the cancer metastases are getting larger. So, I'd say
at very low PSAs, you definitely want to use PSMA, higher PSAs, Axumin is not bad. Another thing
to consider is that in about 10 percent of men, their cancers don't make the PSMA molecule, and so
their cancers are are not going to be showing up on a PSMA scan. So, if someone has a clear PSMA
PET scan and their PSA is high enough to where you think there's significant likelihood of lymph node
metastasis, I think it's a very logical time to get an Axumin PET scan and see if it's a
non-PSMA producing cancer; that the reason that nothing was seen on that PSMA PET scan is not
because there's no cancer there, but because they have a type of cancer that is not making PSMA. So,
we know that's about 10 percent of men with prostate cancer. So, Axumin will still have a role
for those situations, but I think the first go-to scan now that it's FDA-approved and now
it's covered by Medicare, is going to be PSMA. For that small 10% who don't make that PSMA molecule,
are there genomic tests that will tell people ahead of time that they should automatically be
getting it, or is it just that if it doesn't show up in the lymph node involvements there
or the PSA is so high that you're just automatically going to do an Axumin scan?
Yeah, I'm not aware of any assays right now. I suppose one could go back and look at the original
biopsy specimen in the prostate and see if it stains for PSMA, but the problem with that is that
as cancers progress and spread, they change genetically—they can mutate—so it may not
match what was in the original biopsy specimen. So, I think it's just going to be
if we're suspicious when someone has a negative PSMA PET scan, then it'd be logical to get an
Axumin PET scan or a C-11 acetate PET scan which uses a different technology than Axumin does. So,
these other PET scans, both C-11 acetate— C-11 choline, excuse me, and Axumin offer
a different methodology to try and look for lymph nodes in case the PSMA is missing something.
I know one conversation we've been having on our helpline a lot is we talk a lot about PSMA,
but the centers that are doing it are not widespread across the country;
there seems to be a few centers whereas Axumin is widespread in every state, it seems like, and
there's a huge list on their website of centers that are doing it. So, how do you see the— what
rate do you see these centers opening up that are going to start doing PSMA now that it's covered?
Very rapidly. So, the company that—there's actually two companies that make PSMA type PET
scans—I believe one is already commercialized, the other one will probably be commercialized within
six months, so we should probably provide the phone number of that company. People can call the
company and ask them are there centers in their area that either are offering the PSMA PET scan or
are going to be offering it soon, and I think that you'll find that this technology is going
to spread very rapidly at this point. Hey, everybody, it's me and our dog the PCRI mascot,
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