Conventional Versus PSMA Imaging in Prostate Cancer

Daniel J. George, MD: Ben, do you have any thoughts from the community urology perspective? Do you see this becoming widespread in your preoperative work-ups and your high-risk patient population as a way of decreasing our volume of treatment of patients or maybe expanding it?

Benjamin H. Lowentritt, MD, FACS: It’s great question, and I’m very excited to see the application of these novel PET [positron emission tomography] agents in the staging standpoint. From what we’ve had available, outside some of the locations that have an agent they’ve been studying, the commercially available agents are only for biochemical recurrence. This idea of moving into the staging will help us because there’s a lot of variability in how we’re treating high-risk cancer.

It’s personal preference. Everyone is doing the best they can for their patients. It’s not easy to make it data driven when you have what you strongly expect is metastatic disease but you’re hoping might be localized, and you’re getting those patients who can be cured. Anything that gets us to a point where we can be more accurate with our staging is a positive, so we would absolutely want to use these agents for better staging of our high-risk patients when available. I don’t know that it’s going to lead to less overall treatment.

It will just be more specific treatment and even more localized treatment. A lot of people who write some of these patients off because they strongly suspect they have metastatic disease. I also suspect there might be opportunity for cure in a lot of the next-generation, imaging-only, positive lymph node, localized regional disease patients if we treat them appropriately. It’s going to allow us to better evaluate treating and studying these patients going forward. It’s nothing but a positive.

Daniel J. George, MD: Tanya, when we think about metastatic disease, we think about systemic therapies and now combinations—ADT [androgen deprivation therapy] plus systemic therapies. Do you think you’re going to be comfortable doing that on PSMA [prostate-specific membrane antigen] level alone, if there isn’t more traditional bone scan or CT [computed tomography] scan findings? How do you think that’s going to impact our threshold for aggressive combination systemic therapy?

Tanya Dorff, MD: Personally, I think having PSMA-positive disease that’s not visible conventionally and then labeling that patient metastatic and treating them with lifelong, intensified systemic therapy is hard to sell. The added value will be if we can apply local therapy like focal radiation to areas where we see early micro-metastatic disease and try to get back to more of an intermittent approach, which is what we would be doing if only we had the conventional imaging.

Even the modern trials like the Alliance Foundation Trials’s androgen annihilation trial [AFT-19], which is looking at intensified therapy in the setting of biochemical recurrence, are ignoring PSMA PET findings and basing therapy on conventional imaging. At very, very low volume, maybe we don’t need to make that leap. At the least, it needs to be studied before we shift our treatment paradigm.

Daniel J. George, MD: I think that’s right. We have to be careful not to overreact, or patients might overreact. It’s going to be important that we don’t overreact to what these findings are and what they biologically represent, compared with how we’ve traditionally defined high-volume disease and whatnot.

Transcript Edited for Clarity