August - December 2005 Issue
Radiation Therapy: Versatile Tool Against Prostate Cancer
Colleen A. Lawton, MDMedical College of Wisconsin Radiation Ocologist
Named one of the "Best Doctors in America®" 2004 by Best Doctors, Inc.
One of the most versatile tools in treating prostate cancer is radiation therapy. Colleen Lawton, MD, discusses its uses and limitations.
Q. What is the role of radiation therapy in treating prostate cancer?When a man is diagnosed with prostate cancer, there's a role for radiation therapy every step of the way. Let's assume for argument's sake that the cancer is confined to the prostate. Besides surgery, there are two options for radiation treatment — radioactive seed implants or external beam radiation.
Q. How successful is radiation therapy for these men? The success rate is excellent. For patients with favorable, localized disease, it is certainly in the 80 percent to 90 percent range and, stage for stage, grade for grade, it's essentially equivalent to surgery.
Q. What about patients whose cancer has spread?If patients have cancer that has spread to regions around the prostate, radiation continues to play a role as a curative treatment. If the cancer has spread to bone and there is a painful area, radiation plays a role. While prostate cancer cannot be cured once it has spread to the bone, radiation therapy can help make the patient feel better, because it relieves pain.
Q. What kind of research are you involved in?Most of the research we are involved in here is through the Radiation Therapy Oncology Group (RTOG), a clinical trials group sponsored by the National Cancer Institute. I have personally been involved with the RTOG for more than 19 years.
Most recently, there was some exciting work done with patients whose cancer has spread to other areas around the prostate. It showed that adding hormone therapy to radiation therapy results in more cures. We recently became involved with work sponsored by the National Institutes of Health looking at a different way of giving radiation. We are investigating the possibility of giving patients higher radiation doses at each treatment. That would be exciting for patients who live far from a radiation facility, because they would not have to come in as often.
There's also a trial going on right now looking at the potential benefit of Viagra for men who are getting hormones and radiation. Hormone therapy can cause some decrease in sexual functioning.
Q. Any other research highlights?Currently, I’m in the process of developing a new protocol, again sponsored through the RTOG, looking at patients who have benefited from hormone therapy and radiation therapy for what we call locally advanced prostate cancer. You see, there is a downside to hormone therapy in that it can cause osteoporosis. In this study, we’re going to look at how we can address this issue.
In this particular trial, everyone is going to get calcium and vitamin D and then, by the flip of a coin, some people will get a bisphosphonate (a bone-strengthening drug) versus a placebo. We will see whether the drug actually helps bone mineral density or is it just calcium and vitamin D that everybody needs, but nobody is really getting on a regular basis.
Q. What is the future of radiation therapy for cancer?There really are a number of ways that radiation can play a significant role in the future. One of the things that’s been advancing is the way to deliver the radiation, so that we get the radiation where we want it and avoid the structures where we don’t want it.
I think another future direction may be monoclonal antibodies that would be targeted against prostate cancer. In some cases, a radio-labeled substance could be attached to the antibody. The antibody would be attracted to the antigen, which is prostate cancer, with the result that the associated radiation would really target the area where the prostate cancer is. That concept is exciting.
Then there is the whole area of gene therapy — will radiation play some type of role in that? It’s hard to know. That’s one of those “Star Wars” things. Would you want to destroy a genetic abnormality with radiation? Could you somehow use radiation-related genetic changes to your advantage? All we know is the bad things associated with radiation. The problem is I don’t think we have a good enough handle on what goes on genetically in a prostate cancer patient, or any cancer patient, to know what the potential upsides of a radiation mutation could be.
Author: Colleen A. Lawton, MD
Source: Every Day
Date: August - December 2005