Shannon Kahn, M.D., a radiation oncologist and assistant professor at Winship Cancer Institute at Emory University in Atlanta, Georgia, talks about a treatment for tough-to-treat tumors.
Interview conducted by Ivanhoe Broadcast News in May 2017.
I wanted to ask you about the Gamma knife. I know it’s a technology that’s been used over a number of years and it keeps changing and improving. If you could explain what the technology is.
Dr. Kahn: Gamma knife is a machine that delivers radiation. This technology allows for the delivery in a very focused, precise manner. It is most commonly delivered in a one-time treatment session that takes approximately half of a day. The results can be equivalent to having a tumor resected with surgery. You can often obtain similar control rates, without the surgical risks. The side effects of this type of radiotherapy are also much less than more traditional radiotherapy because it can be sculpted and fine-tuned to avoid dose to healthy tissue.
The benefits of doing it this way you’re not actually opening up anything so you’re not having open full surgery?
Dr. Kahn: Many of our patients have other health issues and complicating factors which can make getting through a craniotomy very difficult. In addition, this kind of surgery can interrupt other types of medical therapy, including chemotherapy. Gamma Knife stereotactic radiosurgery provides an extremely effective alternative with little risk and interruptions to their scheduled medical regimen.
Gamma knife is a radiotherapy machine that is specifically designed and only used for treatment to the brain. Because of the conformality of the dose to the target, dose to healthy tissue is minimized. This can avoid such effects such as personality changes, cognitive or memory deficits.
When you’re dealing with the brain, in particular, why is precision so incredibly important?
Dr. Kahn: As neuroscience continues to evolve, we continue to understand the complexity of the anatomy. And we continue to understand that injury to the brain, whether it be from a stroke, tumor, or other causes, can be extremely hard, if not impossible, to repair or compensate. So if damage is done from a tumor, radiation or surgery may not be able to reverse that effect. But what we can aim to do is to perform treatments, such as Gamma Knife, to avoid any further injury from the actual treatment itself.
The Gamma knife that you’re using now is a new version and can you tell me about that?
Dr. Kahn: We have theICON upgrade to the Gamma Knife Perfexion machine. It has been used at our facility since June 2016. We are the third center in the US to have this capability. The ICON allows for Gamma Knife to be delivered to a wider range of tumors that was previously possible. For example larger tumors, or tumors close to critical structures in the brain used to be excluded from this technology. However, the ICON allows a patient to be treated over multiple sessions, with lower doses per session, to allow higher volumes to be treated and to help protect effects to surrounding critical regions.
Prior to the ICON implementation, all treatment were delivered with a head frame affixed to the patient’s skull. This is now delivered with a mask fitted to the patient head with motion monitoring to allow for precise and reliable delivery in a much less invasive fashion.
Can you speak to Joe’s Garrett’s case a little bit?
Dr. Kahn: Mr. Garrett is an extraordinary man and we all loved him immediately. He has a benign tumor but in a very bad position in the brain. This tumor is near the brain stem and nerves that control movement of the eyes and vision. When this is the case, surgically removing this tumors can be extremely difficult and pose substantial risks to injuring these functions. The location is also what would have previously excluded him form a Gamma Knife treatment. However, with the ICON, we were able to divide his treatment among five different sessions to avoid injuring his vision or brainstem and still minimize dose to the healthy tissue. The expectations is that this will control his tumor and avoid any further medical intervention or side effects.
He described it as the tumor was wrapped around a nerve?
Dr. Kahn: His tumor is adjacent to the nerves that control vision and eye movements which explains why he first noticed the double vision. If it continued to progress, his quality of life could have been severely impacted. As he can attest, he has now had this tumor treated and returned to his life with very little effects and now with his tumor growth controlled.
END OF INTERVIEW
This information is intended for additional research purposes only. It is not to be used as a prescription or advice from Ivanhoe Broadcast News, Inc. or any medical professional interviewed. Ivanhoe Broadcast News, Inc. assumes no responsibility for the depth or accuracy of physician statements. Procedures or medicines apply to different people and medical factors; always consult your physician on medical matters.
If you would like more information, please contact:
Mary Beth Spence
678-843-5850
Marybeth.spence@emoryhealthcare.org
Sign up for a free weekly e-mail on Medical Breakthroughs called First to Know byclicking here.