Experts to debate best uses of PSMA-PET in prostate cancer treatment decisions

Interest in PSMA-PET (prostate-specific membrane antigen) has soared since its initial 2020 approval by the Food and Drug Administration. Interest and utilization are up, but opinions on how best to apply this highly specific molecular imaging technique remain divided.

“Advanced imaging for prostate cancer is here,” said Daniel W. Lin, MD, professor and chief of urologic oncology and director of the Institute for Prostate Cancer Research (IPCR) at the University of Washington and Fred Hutchinson Cancer Center in Seattle. “We have multiple guidelines that suggest PSMA-PET can replace conventional imaging, standard CT and bone scans, but how to utilize PSMA-PET to guide treatment decisions in the real world is less than well-defined.”

The problem, Dr. Lin noted, is that most clinical trials for prostate cancer treatments were based on conventional imaging, not on the more recently developed PSMA-PET. As PSMA-PET specific evidence develops, expert opinions on the most appropriate uses remain divided.

Dr. Lin will moderate a Crossfire debate, “Impact of PSMA-PET on Treatment Decision-Making,” during the afternoon Plenary on Friday, April 28, from 2:55 to 3:25 p.m. in Hall B1. The session panel will explore current uses of PSMA-PET in the real world.

Clues pointing to the most clinically appropriate uses of PSMA-PET in multiple clinical scenarios are beginning to emerge from multiple studies, he explained. For now, the strongest case for PSMA-PET may be in the recurrent setting after prostatectomy or radiation therapy. The decision to use PSMA-PET is usually triggered by a rising PSA level. The modality was initially approved in suspected metastatic disease or rising PSA levels.

PSMA-PET is also finding important use in newly diagnosed prostate cancer, particularly for men with unfavorable intermediate and high-risk disease.

“The real question is if you find distant disease on molecular imaging as opposed to conventional imaging, what are your next steps?” Dr. Lin said. “What kinds of drug therapies and treatment plans does PSMA-PET open up or close off for you? Those are going to be major debates on Friday.”

In the absence of PSMA-specific trial data, a few trends seem clear, Dr. Lin continued. Performance seems to be most effective in the setting of rising PSA levels and is not very effective at very low PSA levels for the detection of recurrent disease.

“If someone had a prostatectomy and PSA goes to zero, then barely becomes detectable, we would never use PSMA-PET in that setting because the level is too low,” he said. “If you wait until PSA gets a little higher, it performs much better. But we don’t have a cutoff PSA level clearly defined by clinical trials.

“The session can give attendees practical guidance on when, and in what situations, to use PSMA-PET and what to do with those results,” he continued. “You will leave this session with a better understanding of when to get molecular imaging and what to do with those results in the clinical scenarios we know the most about, recurrent disease and newly diagnosed unfavorable-intermediate and high-risk disease.”