Considerations for Initiating ADT in Prostate Cancer

Transcript:

Raoul S. Concepcion, MD, FACS: Hello, and thank you for joining this OncLive^® Peer Exchange^® titled “Redefining Advanced Prostate Cancer With Novel Imaging.” Androgen deprivation therapy, or ADT, is the mainstay of initial treatment for advanced prostate cancer. But for many men, disease progression, despite castration levels of serum testosterone, invariably leads to endocrine or castration-resistant prostate cancer, also known as CRPC. What we do know is that the androgen receptor axis continues to drive disease progression in many of these patients. Despite multiple approvals, over the past 7 years, for therapies in metastatic CRPC (mCRPC), these therapies have not been approved for non-metastatic castration-resistant prostate cancer (m0CRPC).

In this OncLive^® Peer Exchange^®, I am joined by a panel of experts in the field of genitourinary oncology. In today’s discussion, we will define 4 phenotypes of advanced prostate cancer and will provide practical definitions for these patient subtypes. We will also discuss the availability of next-generation biologic imaging and how these novel agents may affect these current definitions, as well as treatment choices in advanced prostate cancer.

I’m Dr Raoul Concepcion, the director of the Comprehensive Prostate Center in Nashville, Tennessee. Participating today on our distinguished panel are: Dr Daniel George, director of Genitourinary Oncology at Duke Cancer Institute in Durham, North Carolina; Dr Alec Koo, a urologist with Skyline Urology in Southern California; Dr Phillip Koo, division chief of Diagnostic Imaging at Banner MD Anderson Cancer Center in Phoenix, Arizona; and Dr Neal Shore, a medical director for the Carolina Urologic Research Center in Myrtle Beach, South Carolina. Thank you so much for joining us. Let’s begin.

Gentlemen, in this first segment, what I thought we would do is, again, give our audience sort of some working definitions and sort of management schemes on the various phases, as patients progress, in the whole journey of prostate cancer. So, in this first segment, let’s talk about biochemical-recurrent hormone-naïve nonmetastatic prostate cancer patients.

Again, these are patients who have been definitively treated. Depending upon the Gleason score, at the time of diagnosis and treatment, we know that there are certain risk factors that those patients have, despite definitive therapy. They are going to progress and have a biochemical recurrence or a rise in the PSA [prostate-specific antigen].

Alec, you’re in southern California. You’ve got a fairly large group down there. Actually, it’s a very interesting group. You have incorporated a lot of different specialties, which we’ll talk about later. When you manage these patients, either after radical prostatectomy or cryotherapy, and you see a biochemical recurrence, what are the triggers that you use to determine when to start androgen deprivation therapy?

Alec Koo, MD: There are probably several subtypes. In post—radiation therapy patients, you have a nadir. There are probably different definitions for when to consider it a biochemical recurrence versus the post radical prostatectomy. Post–radical prostatectomy patients should have a PSA of 0. Any rise in PSA is the signal that there’s biochemical recurrence. With postradiation therapy, you really need to reach the nadir. There are different sets of definitions. But maybe twice the nadir value.

In any case, when this occurs, patients are obviously highly anxious. As the physician, you’re really charged to evaluate a situation and advise them. Typically, because of the patient’s anxiety, as well as the physician wanting to treat and facilitate the patient’s process through this, the traditional thing to do is start thinking about when to order bone scans and a CT scan. We all know that at low PSA values, bone scans and CT scans aren’t necessarily that sensitive to pick up metastatic lesions. Typically, you wait until it reaches a certain level. But that level is variable. It’s highly variable, based on the patient. It’s really a shared decision process.

With the availability of the new imaging modalities, which I think is the focus of the conversation, that has really shifted. At least in my practice, we obtain bone scans and CT scans. When they’re negative, that’s when we go on to the more advanced imaging. We’re lucky enough to have fluciclovine PET/CT scanning in our area, and that has proven to be very valuable.

Raoul S. Concepcion, MD, FACS: Neal, is there anything to add to that?

Neal D. Shore, MD, FACS: No. Alec takes on a summary of a complicated issue with regard to what their primary intervention was. And historically, we have kind of reflexively said, “OK, biochemical recurrence. Let’s institute androgen deprivation therapy.” And over time we’ve recognized that it’s not a free lunch. ADT has a lot of consequences—from cognitive dysfunction to hot flashes to loss of sexual function to visceral weight gain to quasi metabolic syndrome. So, I think there’s been a real pendulum shift to say, “What can we do to avoid that reflexive ADT?” As Alec mentions, and I know Phil Koo can talk at great length about the fluciclovine test, why are we getting it? Maybe it’s now a great opportunity to treat low-volume recurrent disease with either radiation therapy or, possibly, surgical extubation. You know, these oligometastatic disease states rather than reflexively starting with ADT. We don’t have a lot of level 1 evidence for it, but there are a lot of studies that are looking at that. I think that’s a really important take-home message for the audience to recognize. A lot of this data will be forthcoming.

Transcript Edited for Clarity