Metastatic Castration-Resistant Prostate Cancer: Optimal Imaging Strategies


Expert oncologists define appropriate imaging strategies, conventional and novel, in patients with metastatic castration-resistant prostate cancer.


Evan Y. Yu, MD: We've talked about imaging, Mary-Ellen I'm going to ask you about this patient's imaging. The patient did have a bone scan and interestingly, the patient had an FDG PET/CT. You want to tell me, what are your thoughts on still using bone scans, when are you incorporating FDG PET imaging and when would you get a PSMA PET for this individual?

Mary-Ellen Taplin, MD: We're in a transition state here in the US [United States] with imaging and I would say, honestly, I'm still trying to figure it out. In metastatic CRPC when I would get a molecular imaging such as a PSMA PET scan, a lot of my patients have had conventional imaging. Up to this point we're evaluating them and there's a whole comparing apple to apples thing. You know how they've, their disease, has progressed and responded over the last couple years. Do you want to switch to a PSMA PET which would be without a baseline? If I have a patient who's had consistent conventional imaging and at this point have been sticking with the conventional imaging. If I have a patient who I think has potential for very low-volume progressive disease because their PSA has just started to go up or they've only had low volume disease in the past, then I would probably consider doing a PSMA PET scan on a patient like that. As somebody mentioned it earlier, but there is the whole getting a prior authorization covered for PET scans which is taking up an inordinate amount of time I would say in our practice with trying to negotiate payment for the scans for these patients. If I'm offering a PSMA PET scan to a patient, I will try to alert them to that upfront that it may be possible in the end that we won't get coverage for it and they'll hopefully understand and not be disappointed that we might end up doing conventional imaging even if we're starting out trying to get a PSMA PET scan. FDG PET, I don't typically use. I did do a trial years ago and FDG PET is a very good scan in CRPC, not in hormone sensitive or early prostate cancer, but it's not commonly used, and I don't typically order it.

Andrew J. Armstrong, MD, MSc:Like Mary-Ellen, I tend to order the test only when I'm going to act on it and with PSMA lutetium being available, that's going to have a management change. You've got choices between cabazitaxel and PSMA lutetium. And Michael Hoffman had great data from the GU symposium and today at ASCO [American Society of Clinical Oncology] that the PSMA PET perimeters may be predictive of that treatment selection. The data from the vision might be prognostic in helping to identify patients that can have a more deep and durable response from PSMA targeting therapy. An FDG positive lesion that's PSMA negative, that's probably a cabazitaxel patient.

Evan Y. Yu, MD:Are you starting with FDG PETs, with your PS maintenance?

Andrew J. Armstrong, MD, MSc: No, no. I would if I was concerned about small cell.

Evan Y. Yu, MD:I am.

Andrew J. Armstrong, MD, MSc: If I was concerned about small cell, I would do it, particularly liver metastases. Lung metastases tend to be a more favorable prognosis. I don't necessarily think of them in the same category as the liver metastases. But, for certainly in a visceral patient or a patient with low PSA but high disease burden I would do it.

Evan Y. Yu, MD: I'll just say that I tend to start, I'm starting to, when I do PSMA PETS do FDG PETS together. But I tend not to do it early mCRPC. Later, like in the post chemotherapy setting, I'm starting to use that.

Andrew J. Armstrong, MD, MSc: It can be helpful.

Transcript edited for clarity.

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