So, Dr. Scholz, there are different assays in prostate cancer, you know,
we have the 4K score, we have ExsomeDx, we have FoundationOne, PCA3,
you know, PHI [prostate health index]. We have all sorts of assays. So, first of all,
can you explain to the audience what an assay is, and then also which are the most useful and when?
The majority of what you mention is to help people decide what to do when their PSA is
elevated in men that don't know that they have prostate cancer. There's a great need
in this space because no one wants to go through a 12-core random biopsy if they don't have to. The
disadvantage of these tests is that they only give an answer in percentage terms, and people aren't
interested in percentages unless they're very extreme — "Well, there's a 27% chance you have
serious cancer," not helpful, you're still going to have to get a biopsy to make sure that there's
no cancer. The assays that we've relied on most are like OPCO 4K which is a blood test, SelectMDx
is a urine test, and if the percentage is extreme, let's say that the indication is that there's
less than a five percent chance that there's significant cancer, then that may be enough
to avoid doing a biopsy or even avoid doing an MRI which we always do before a biopsy.
These have some application, unfortunately, in most cases, the percentages aren't extreme
and the tests don't really give us much help in deciding what to do and we end up having to do an
MRI and sometimes a targeted biopsy to further evaluate the situation.
Out of all those tests I mentioned, though I know that we mention the 4K score the most
when it comes to having a high PSA, so how does the 4K score work, and have you ever
seen that be able to work in a way that you know it would change the course of treatment?
Yeah, so all they do is draw your blood and they test a bunch of enzymes and there are
certain enzymes that are associated with higher-risk prostate cancer, clinically
significant prostate cancer, and they then tell you that there's x percent chance of clinically
significant prostate cancer and that is useful if the percent is very very low, let's say less than
five percent chance of clinically significant prostate cancer. Under those circumstances,
if there is no palpable abnormality on digital rectal and the PSA is not ridiculously high,
people can simply go on screening and skip doing a biopsy which is wonderful.
In my experience, these tests don't read out at such low levels very often — maybe one out
of five, one out of ten men. So you do a lot of testing to find one person that can skip
getting evaluated with a biopsy or an MRI, but it's valuable for that individual. So,
we do utilize these tests, but since they're not consistently useful we're
not finding that it helps the majority of men; it does help a minority of men.
So, it sounds like that every man does need to be tested with these
though because it doesn't sound like we can determine the minority of men that
these tests would be really useful for ahead of time, is that accurate?
Um-hmm, that's true.
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