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Alicia Morgans: Hi, my name is Alicia Morgans and I'm a GU Medical Oncologist at Dana-Farber Cancer Institute in Boston. I'm so excited to have here with me today, Dr. Tanya Dorff, who is an Associate Professor of Medicine and the GU Section Head at The City of Hope. Thank you so much for being here with me today.

Tanya Dorff: Thanks for having me.

Alicia Morgans: Wonderful. Well, I wanted to talk with you a little bit about current updates to the NCCN guidelines around PSMA imaging, which were recently reported, and I think do tend to broaden our scope in terms of options for imaging modalities for men with prostate cancer. So can you tell us a little bit about the recent changes?

Tanya Dorff: Sure. The NCCN was looking at all these new studies that have been reported out with the two different PSMA-PET tracers, the gallium-68, as well as the DCFPyL-18 based PSMA tracer. So there have been a lot of studies in locally advanced or high-risk localized prostate cancer, where it just really seems like we see more disease that could impact how we want to manage a patient. So whether we see regional lymph nodes, for instance, could guide the design of radiation fields or which lymph nodes are sampled at the surgery.

And those practical implications haven't necessarily been validated, and yet the PSMA-PET scan has been validated for accuracy. In some of the trials, they actually sampled areas that were PSMA-PET-positive to confirm, or there were some other lower grade confirmatory evaluations of the performance. But bottom line, it is far more sensitive, very specific, and quite accurate. And so we do think that for these higher-risk localized patients, that it can be beneficial.

The other area where it was looked at was in biochemical recurrence. So we know that a conventional CT or bone scan is probably not going to detect prostate cancer until PSA is several digits. So somewhere on the order of maybe three, four, or 5.0 PSA. And yet, we're trying to make decisions far earlier for patients when their PSAs are 0.4, 0.5 before starting salvage radiation for instance. And so that higher sensitivity that has been proven in many different studies now really can benefit us by understanding whether a patient has truly biochemical recurrence that we can't even see with the PSMA-PET or is better categorized as visible metastatic disease.

Alicia Morgans: I think it's so interesting and important. And I appreciate that the sensitivity and specificity are better, but I wonder how has the NCCN really provided guidance around whether we still need conventional imaging to be done before we get these scans or after to confirm them? Is there a requirement for using multiple modalities of imaging techniques if we have the information that we need from a PSMA- PET alone?

Tanya Dorff: So that's a great question. Elsewhere, in the world, they just use the PSMA-PET and they do not use the CT and bone scan anymore. NCCN certainly views it as a test that can be helpful if you have equivocal findings on conventional imaging. However, ultimately it's not felt that you really need that conventional imaging because that's extra radiation exposure for patients, extra cost, extra time. If you can really get all the information you need for both bone and soft tissue using one PET scan, then it does seem to be the most efficient way to go about doing the imaging.

Alicia Morgans: Well, I think that is a really reasonable approach and certainly will have implications in the clinic. And I think that we all will have to look forward to seeing how everything shakes out in terms of being able to actually order these and get these in the clinic. But it is wonderful to know that the NCCN is right on top of things and is making very timely adjustments to its guidelines. So if you had to summarize that guideline or the guidance around PSMA-PET imaging, just briefly, what would that be?

Tanya Dorff: Yeah. So I think the bottom line is that PSMA-PET scans can be used independently in the setting of staging, for instance, for biochemical recurrence. They can still be helpful when there's an equivocal finding on conventional imaging, but you don't necessarily have to get the conventional imaging because they are felt to be quite accurate and sensitive. For high-risk localized, I think it's more likely that conventional imaging such as an MRI will have already been done, right? As part of the pre-biopsy workup even, but the PSMA-PET can add above what is seen on that MRI.

Alicia Morgans: Great. Well, thank you so much for your time and for walking us through this.

Tanya Dorff: My pleasure.