Declan Murphy, MB, BCh, on Rate of Equivocal Findings on PSMA PET/CT in Patients With Prostate Cancer

Murphy discussed the secondary end point of equivocal findings on PSMA PET/CT from the proPSMA study presented at the SUO 21st Annual Meeting.

Professor Declan Murphy, MB, BCh, of the Peter MacCallum Cancer Centre, spoke with CancerNetwork® about the rate of equivocal findings in the proPSMA study for patients with prostate cancer undergoing prostate-specific membrane antigen (PSMA) PET/CT imaging.


At the SUO [Society of Urologic Oncology 21st Annual] Meeting, I was asked to talk about PSMA for upstaging because, traditionally, that’s what people see with PSMA PET/CT. You do a scan in a patient and you don’t see any cancer outside the prostate. Then you cross over and have a PSMA PET/CT and you see additional lymph nodes or even distant metastases. Traditionally, we think it’s picking up stuff that conventional imaging does not, but there’s an additional factor which is why we emphasize that its accuracy, not especially upstaging, that matters. We show in proPSMA a secondary end point [of] the rate of equivocal findings, and in conventional imaging, 23% of our patients had equivocal findings on CT or bone scans.

What does that mean? This is all too familiar territory for anyone out there looking after [patients with] prostate cancer. You do a CT or a bone scan and the report comes back saying equivocal bone lesion in the rib or [other area]. We see that in 1 in 4 patients, and so what that leads to, of course, is uncertainty which needs to be resolved. Then patients traditionally will go on and have novel imaging or an MRI scan or even a biopsy to clarify that. That’s a high rate of equivocal findings, whereas in the PSMA PET/CT arm we see equivocal findings in only about 6% or 7% of patients. As a secondary end point, we think this is very important. We understand equivocal findings are very common, proPSMA confirmed that, and this creates uncertainty and leads to further investigation. This needed to be clarified, the rate of equivocal findings, and it was much better [in the trial discussed herein].