USANZ 2017 – Dr John Davis
John W. Davis, MD is Associate Professor and Director of the Urosurgical Prostate Program, Department of Urology, The University of Texas MD Anderson Cancer Center.
John gave the BJUI lecture discussing the role of prostate cancer genetics and the role of the genetic tests that are currently available.
Talking Urology podcast transcript
USANZ 2017 Interviews – John Davis
This is Talking Urology.
Joseph Ischia: I’m Talking Urology with John Davis. He is the Associate Professor of Urology at the MD Anderson Cancer Center in Texas in the States. He has very kindly agreed to join us to give us the highlights of his talk which was the BJUI lecture on prostate cancer genetics. John, what were the highlights?
Dr. John Davis: Well, for many years we’ve talked about getting more genetic testing into prostate cancer to try to risk stratify patients and there are two basic decision points where that might be helpful. One of course is patient who might be a candidate for active surveillance versus intervention. And even the folks who go through surgery you might then want to risk stratify who should be observed versus do postoperative radiation. I learned along this journey, you know, some terminology that’s helpful. There are commercially available biomarkers in the U.S., some in Europe, and they’re mostly what we call prognostic markers meaning they can help risk refine the odds of an event happening. Now my colleagues in medical oncology look at this differently and they mainly emphasize predictive markers where a biomarker’s efficacy is linked to the drug working or not working. But in prostate cancer, we can still get some information out of prognostic markers; one for example is Prolaris that looks at cell cycle progression genes. If they’re extremely aggressive looking or extremely non-aggressive looking, that may help break the tie between surveillance radiation.
Joseph: And this is on biopsy specimens, isn’t?
John: It is on biopsy and for the most part they’ll work on very small amounts of tumor. You can have, I mean, if you literally have less than a millimeter of Gleason 6 you probably can’t run the test but a little bit more than that you should be okay. And, you know, the company’s design trials differently with different endpoints so another one called Oncotype looks at the risk of having unfavorable prostatectomy, you know, high grade T3 stage. So, I sometimes use that in young patients where you know any degree of unfavorable pathology you know in a 50-year-old would be not a good candidate for surveillance for example. In the postop setting what is interesting is there is a third marker called Decipher that really hones in on the risk of metastatic progression and they’ve also been able to retrospectively link that to postoperative radiation. So in simple terms if they’ve got a favorable Decipher profile you probably put them on observation even if they have a positive margin or T3 stage. But if they have an aggressive Decipher, that’s about 20% of the high risk population, then they clearly have a better durable response to radiation if it was given adjuvants. And for us, that’s a valuable question because as a default most of our patients don’t want adjuvant radiation unless you can give them a really strong argument that they need it, so this can help us with that.
Joseph: These tests sound really useful, but they don’t seem to have really taken off, why is that?
John: I think the competing space concept is using MRI and biopsies for example in the active surveillance area. I don’t know why the Decipher wouldn’t take off because you know, in the U.S. it’s about a $4000 test but you’re asking it to tell you whether or not you need in our term is $50,000 with a postop radiation. Now in the biopsy world, it’s understandable because if you’ve got high quality MRI and fusion-related biopsies you may prefer to use that to differentiate who needs surveillance versus treatment. In the U.S., high quality MRI is not universally available. It’s really in high volume centers whereas if they run a genetic profile it’s the same profile regardless of where it comes from because these go to referee labs. So you know each practitioner would have to see what resources and talents are available to them and you know sample and figure out which one helps them make these difficult decisions. Again, clinical utility is a bit of an eye of the beholder. If you have a patient whose mind is made up maybe you don’t need any more information. But I’m sure we all experience patients who are indecisive and they want as much information as they can get their hands on.
Joseph: I’ve certainly know a few of those. Thank you very much, John. You’re very kind and great to have you here in Australia. Thank you.
John: Great meeting, thanks.