Declan Murphy, MB, BCh, shares his thoughts on the potential for prostate-specific membrane antigen PET/CT to impact outcomes for patients with localized and high-risk prostate cancers.
Declan Murphy, MB, BCh, of the Peter MacCallum Cancer Centre, spoke with CancerNetwork® about the secondary end points from the proPSMA trial that was presented at the Society of Urologic Oncology 21st Annual Meeting and the currently unknown data regarding how the change in management for superior imaging will lead to improved outcomes for patients.
While the primary end point of proPSMA is very clear [in showing] that PSMA [prostate-specific membrane antigen] PET provides more accurate information compared with conventional imaging, that’s clearly not the end of the story. There are a few important secondary end points that lots of people have noted since the paper was fully read out in The Lancet earlier this year, one of which is management impact. At each time point during proPSMA, we assessed the clinician plan for that patient. Just after diagnosis [and] before any imaging, we measured the plan.
The study was set up so that half the patients had conventional imaging first and half had PET scans first and then they [all] crossed over. We could measure the impact of each line of imaging, and what we saw was that, unsurprisingly, PSMA PET/CT was very impactful in about 27% of cases in first-line imaging and even in second-line imaging. If you had a CT and a bone scan first, there was about a 5% to 6% management impact; but when you cross over to PET/CT, there’s still a further 27% impact. The extra information is clearly impacting what clinicians are suggesting to their patients.
But of course, one of the great unknowns is whether that change in management based on superior imaging will lead to an improved outcome for that patient. We already knew that was going to be something we couldn’t measure in proPSMA. It’s not even one of the end points in proPSMA because it is a real challenge in localized prostate cancer, albeit high-risk prostate cancer, to measure something that may take 10 or 15 years to mature. The whole community of [clinicians treating] prostate cancer around the world will have to tackle the fact that management impact will be very significant with better information, but it will be difficult to measure the outcomes for patients in terms of improved cancer-specific survival, for example.