Prostate cancer screening: A novel risk prediction tool with standard biopsies vs PSA with MRI-targeted biopsies

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Published: 20 Jul 2022
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Dr Lars Björnebo - The Karolinska Institute, Solna, Sweden

Dr Lars Björnebo speaks to ecancer about a talk he presented at EAU 2022 about a novel risk prediction tool with standard biopsies vs PSA with MRI-targeted biopsies for prostate cancer screening.

He explains that a new model called the Stockholm-3 test could be used to skip the MRI step - something that would be very useful due to issues with availability.

Dr Björnebo reports that the study showed that the Stockholm-3 test found the same number of significant cancers as the PSA with MRI-targeted biopsies route.

However he notes that it does also flag some of the more insignificant cancers but that its still a good option and better than just using PSA followed by biopsies.

When it comes to prostate cancer, there’s a lot of work that is being done now in screening purposes.
So you want to be able to find aggressive prostate cancers early on but you also don’t want to find the
non-aggressive prostate cancers that lead to unnecessary treatment. As we speak, PSA screening is
being implemented in Sweden and PSA is a marker in the blood for the risk of having prostate cancer.
So if you have a high PSA then that would normally lead to performing an MRI or going straight to
doing a biopsy.

What we did in this study was we compared different screening options for prostate cancer. One of
the options was that you took a PSA and if the PSA was elevated you did an MRI, magnetic
resonance imaging, of your prostate. Then, depending on what the MRI showed, if it showed a lesion
then you did a biopsy of that specific lesion and you also did randomised biopsies of the entire
prostate. But if it didn’t show anything then you wouldn’t have to undergo the biopsy. That was one
strategy and the other strategy, that was to use a new test, a new test called the Stockholm-3 test.
This new test, it has some different parameters to it, so it has clinical variables such as age, heredity
for prostate cancer etc. and then it also has genetic markers to it and also some other PSA
derivatives. What you can do then with the test there, or what we thought we could do, was then you
could use that instead of PSA to select which men you should do a biopsy in. So if you have an
elevated Stockholm-3 test then could you skip the MRI step and go straight to biopsy because MRI for
the prostate, it has a lot of value but it also has some issues with the availability because you need a
lot of expertise, you need also a lot of equipment but then you need expertise, for example a
radiologist looking at the scans, you need expertise in the urologist performing these targeted
biopsies. So it’s a step, it’s a sort of bottleneck, the MRI step.

In this study we looked at these different strategies and this was a randomised design. Basically what
we found was that if you do the Stockholm-3 strategy without the MRI you are able to find the same
number of significant cancers, however, you do find quite a little bit more of the insignificant cancers,
the ones that you don’t want to find. So it comes with a price too. So it doesn’t get you all the way
there but it’s still quite a bit better than if you would only do the PSA followed by biopsies which would
be the other alternative if you didn’t have the Stockholm-3 test.

What are you concluding from these results?

Basically the conclusion is that in a setting where you have very limited access to MRI you could use
the Stockholm-3 test to find the same number of clinically significant prostate cancers. So if you’re in
a region where you have a lack of MRI then this could be an option because we like to think it’s a lot
easier to send a blood sample than to send the patient for an MRI scan. For example, we’re
implementing the Stockholm-3 test right now in Norway and they are sending the Stockholm-3 tests to
a lab in a part of Sweden. So the logistics of it seem to work there.

Are there any plans to develop the test further to better find the more aggressive cancers?

Yes, it already does that to a certain extent. If you compare it to just doing the PSA the Stockholm-3
test has a better ability to find these more aggressive cancers compared to the non-aggressive
cancers. But it doesn’t get you all the way there, though, with the MRI. But there’s another study that
has been published by my… it was last year in Lancet Oncology we showed that by using the
Stockholm-3 test you can also reduce the number of MRI scans that you need. So that compared a
strategy where you would use the Stockholm-3 test to differentiate which of these patients do we send
for the MRI scan. So you can use it for different purposes like that.