Host: Dr. Linda Austin – Psychiatry
Dr. Linda Austin: I’m Dr. Linda Austin. I’m talking, today, with Dr. Harry Clarke who is Professor of Urology at MUSC. Dr. Clarke, let’s talk about another way of surgically treating prostate cancer, brachytherapy. What is brachytherapy?
Dr. Harry Clarke: Brachytherapy is a fancy word for placing little radioactive seeds into the prostate through small needles. They’re encoded in titanium. They’re little metal seeds. Essentially, they’re little bullets. And, inside the bullet is one of two isotopes, Iodine-125 or palladium. The difference in the two seeds is the specific activity and the rate of decay. The iodine seed has a little longer rate of decay and a little lower specific activity. The radiation oncologists stratify the patients and they use these two isotopes.
Dr. Linda Austin: Meaning?
Dr. Harry Clarke: They use the iodine seeds for patients with a lower grade disease, and they use the palladium seeds for patients with a higher grade disease. When I say grade, I should clarify that. It’s not really grade as we are usually talking about in terms of pathological grade, or disease. They stratify the patients into favorable category versus unfavorable category, the favorable being those patients that have a low PSA (prostate-specific antigen) and/or a low Gleason score, the unfavorable group having a higher PSA and a higher Gleason score.
The patients with a low PSA and Gleason score get iodine seeds, and they have, what we call, primary brachytherapy, which is, they just have the seeds implanted alone with no other concomitant treatment. The patients with unfavorable disease get a number of months of hormone therapy, one of the LH-RH agonists, one of the chemicals that blocks testosterone, and they get the palladium seeds implanted. In addition to that, they get a number of weeks, usually about five weeks, five days a week, of external beam radiation therapy. So, it’s sort of a sandwich technique where they get implantation of radiation plus some external radiation, and the hormone therapy, to ensure maximum efficacy for the higher grade disease, or the more unfavorable disease.
Let’s just talk about the iodine implant with the favorable disease. That’s a patient who is, obviously, a surgical candidate, not a patient who you would recommend watchful waiting for, who has decided that they would prefer to have one of the minimally invasive treatments, as opposed to having an open surgery, or any type of surgery for their prostate cancer.
The way this is done is the prostate is measured. We need to know what the volume of the prostate is so that we can kno