Dr. Greg Gagnon: CyberKnife as Stereotactic Radiosurgery - [Video Transcription]
- CyberKnife is described as stereotactic radiosurgery? What is that?
"Stereotactic" comes from two Greek words. Stereo means three dimensions and "tactic" is technique. Tactic is like tactic in a military campaign. Central to that is that beams would come from three dimensions to target a tumor. That is the central for stereotactic radio surgery. Some radiosurgery devices out there don't have the two to three dimensional capability which I think is essential. Radiosurgery simply means radiation. Radio is radiation. These are radiation beams. They are precise very small radiation beams. That is the effective agent here.
- How is the CyberKnife easier on the patient than other radiosurgery techniques?
The interesting notable difference with the CyberKnife is that the patient is allowed to move. It is a totally different concept. If you are going to have the patient free to move, then you need an accelerator or radiation device that is not only very precise, but also capable of very exotic movements to trace what could be a very exotic patient movement. On top of that, the tumors outside the brain can move with respiration, heart beats, and a variety of movements. An ability to track that would be very desirable.
- Where in the body is CyberKnife most effective?
We have done it all over the body. We first started up in the brain. We treated a number of cases in the brain. We can do as well or better as I mentioned in other radiosurgical devices. One place in the brain that is most notable is acoustic neuromas and meningiomas. These are benign tumors that grow that tend to grow in very exotic shapes. If you remember, I talked about spherical tumors being easy to treat. When you have a tumor that is not spherical, it is very complicated to treat. I think the CyberKnife is great at treating that. On top of that, we treat the acoustic neuromas which are tumors that grow around the nerve that controls hearing. These are very common benign tumors. We treat them typically with fractionated radiosurgeries. We give a couple treatments. It is believed to improve the hearing preservation rates in the patients. In our surgeries, we have very good hearing preservation and local control in these patients.
- I've heard that Georgetown University Hospital has two CyberKnife machines. How will that help me as a patient?
It is a very effective treatment largely wherever we treat. Our local control rates are excellent wherever we treat be it the spine, brain, or elsewhere. We are looking at a lot of different sites. We treat the pancreas and liver for these different tumors. We have a large series of treating the spine. We have been somewhat limited with only one CyberKnife. We have been treating for very long hours and there have been patient waiting lists to get on the treatment unit. So, we purchased a second one to alleviate some of the strain on the system and the patient waits. The second CyberKnife will allow us to expand out treatment indications a little bit. We have been a little reluctant to expand much of our prostate program. In addition, we are also looking at CyberKnife for breast cancer treatment. We were reluctant to do that when the first CyberKnife was so over utilized. With the second one, we have the space and time to expand our indications.
- Why are the many years of experience Georgetown has with CyberKnife beneficial to me?
The CyberKnife is not a simple technology. It is about as technologically complicated as a treatment can get. We have plenty of physicists, competent therapists, and a group of physicians that are trained and have been doing this for a period of time. It is essential to be doing this correctly. It is a time consuming and technically challenging sort of treatment. That is stuff that the patient usually doesn't see in the background the necessity of having some very bright people working hard to maintain it and make it safe.
- I have heard that CyberKnife is "experimental." That's not true?
The technology is not experimental. It is simply radiation delivery. It had FDA clearance back in 2001. So, we know what the technology can do. We have measurements that we do daily on it and it is very well characterized. So, it is simply a way to deliver high dose radiation to different areas. There is literature out there that supports high dose radiation in a number of areas in the body. So, in many cases it is not experimental. We use data that has been out there for years or more recent data.
