Dr. Phillip Koo is Division Chief of Diagnostic Imaging at the Banner MD Anderson Cancer Center.
Prostatepedia spoke with him about imaging recurrent prostate cancer.
Prostatepedi:Some imaging occurs when men are first diagnosed. When, after treatment, do they encounter these newer imaging techniques? After a high PSA reading? Or just a part of routine follow-up?
Dr. Philip Koo: That’s a really tough question because imaging has a role throughout the continuum of care for any prostate cancer patient. Screening currently isn’t done with imaging, but there are a lot of research studies looking at it.
Prostate MRI is most often used for the detection of local disease. Oftentimes, patients with a rising PSA and a negative standard biopsy might get an MRI or an MRI-guided biopsy.
Bone scans and CT scans are used to help detect metastatic disease. There are many different scenarios, but usually after patients are diagnosed with cancer, most will visit radiology if there is a suspicion for metastatic disease. If we refer back to the RADAR 1 paper published in 2014 by Dr. Dave Crawford in Urology (see Urology 2014 Mar; 83(3): 664-9), we talk about imaging patients at initial diagnosis and imaging those who are intermediate or high-risk. In those patients, we recommended a bone scan and a CT scan.
Patients who are biochemically recurrent may also be imaged. Again, MRI will often be used to look for locally recurrent disease. Bone scans and CT scans are used to look for metastatic disease.
What about some of the newer imaging techniques?
Dr. Koo: The newer techniques are exciting. In both the patient community and the scientific community, we’ve heard a lot about these tools over the past decade. They weren’t widely available, especially in the United States. These newer imaging tools are simply better, which is why there is so much excitement. They will pick up more sites of disease at lower PSA levels.
When we do detect sites of disease, they’re more specific. Our confidence that these sites are actually disease is higher than our confidence when we’re using traditional bone and CT scans. These tests perform at a higher level compared to standard imaging.
Another benefit to these new tools is that in one single exam, we’ll be able to detect soft tissue and bony disease.
How do these newer techniques change treatment? If you can pick up the disease at a lower PSA is that going to change how a doctor treats a man?
Dr. Koo: Yes. We will be able to detect disease sooner. Currently, these newer imaging techniques are used mostly in patients with biochemical recurrence. When a patient has biochemical recurrence and we see the PSA rise, our standard imaging techniques are often not good enough to detect metastatic disease. The problem is that the radiation oncologist or the urologist needs to decide how they want to treat the patient.
Using these newer tools, we can provide the urologist or radiation oncologist with better information about whether or not the disease has spread at the time of biochemical recurrence. If it has not, and the urologist can perform salvage cryotherapy or a radiation oncologist does salvage radiotherapy, we could potentially cure the patient.
Dr. Koo: You’re hitting the disease before it spreads, so theoretically yes. These newe imaging techniques do better, but we really need to prove why this is important and how this impacts care. The answers to these questions will solidify the utility and value of these imaging techniques for prostate cancer patients.
If a patient gets the Gallium-68 PSMA or Axumin scans will his local urologist or oncologist know what to do with that information?
Dr. Koo: Maybe. The problem is that all of this sounds great: we have a tool that can detect disease sooner, better, and more accurately. But then the more important question is what to do with that information and does it impact outcomes. If we don’t know, then what is the value of that imaging tool? We operate under the assumption that earlier detection is always better, but we’re learning that in a lot of diseases that is not always true.
We could be over-diagnosing and over-treating certain diseases. Whether it’s imaging, urology, radiation oncology, or oncology, it really is a team effort because we all bring something unique to the table. We really need to work together to make sure we come up with the best plan and the best answers.