Drs. Adam Kibel and Paul Nguyen explain how PSMA PET imaging is transforming prostate cancer care by helping identify cancer spread in patients with higher-risk or recurrent disease, while emphasizing that clinicians are still learning the best ways to use this information to guide treatment decisions.
Dr. Adam Kibel:
If somebody has abnormal lymph nodes on their imaging when you're evaluating for localized disease, that person clearly deserves a PSMA PET to see what's going on. Somebody who has very low risk disease, I actually think it's a complete waste of money, time, effort, and can actually, believe it or not, cause harm because you identify something that may be abnormal and you have to do this huge workup and then it turns out to be nothing.
It's the patients in the middle, the patients that have say Gleason four plus three, patients even ... I personally like to use them for patients who have Gleason eight, nine and nine cancer. I think it is very useful, but we're even there, even though it's useful, we're still trying to figure it out because again, we get the information and then we have to decide how we're going to act on it. And sometimes I worry that there are patients that had treatable disease that we back off on the aggressive treatment because the PSMA PET looks positive and it might not be.
I mean, again, I think in the next few years we'll iron this out and we'll be able to integrate it much more concretely into our practice with knowledge, but right now we're still trying to feel our way around it.
Dr. Paul Nguyen:
PSMA PET has been another one of those amazing really revolutionary changes that have come along in prostate cancer over the last two to three years. Much like molecular testing, it's just been such a wonderful thing for us to have in the toolkit to try to understand what's going on with patients in their disease state.
So when I personally think about PSMA PET, I think of two disease states. So one disease state is for patients who are newly diagnosed with high risk prostate cancer. So patients who have Gleason 8 to 10, or their PSA is greater than 20, or their MRI shows that the disease has grown through the prostate, which is called extracapsular extension or seminal vesicle invasion. For these patients, there is some risk that there's disease in the lymph nodes or maybe a little bit of spread to the bones.
And I find that PSMA scans can be useful in identifying small bits of disease that we can now incorporate into our treatment planning. So as a radiation oncologist, I could potentially cover those areas of disease. Or if a surgeon is thinking of taking the patient to surgery and they see on a PSMA scan that there is a lot of disease that they didn't know about previously, then that might cause them to counsel the patient differently about whether surgery is really a good idea or not. So I think that's one really useful setting.
The other useful setting that I use PSMA PET in is for patients who have had their prostate removed and now the PSA seems to have come back and it's rising again. Because as radiation oncologists now, we're trying to figure out where the disease is. And when we do radiation, we tend to go to places that statistically speaking, we know historically have been hiding disease. That's where we radiate.
But what the PSMA PET can potentially allow us to do is actually see where that patient's disease is. It doesn't work all the time and your PSA has to get up to a certain level before we can have a realistic chance of seeing something. Usually I get it when the PSA is about 0.25 or higher. But when we do see something, we know from studies that came out of Emory University, Ashesh Jani, the EMPIRE trial, that using that PET scan data to really refine our radiation leads to better outcomes.