Bernard R. Bendok, MD, Chair of Neurosurgery at Mayo Clinic in Phoenix, Arizona discusses how using mathematic equations could help doctors operate on patients with brain tumors.
Interview Conducted by Ivanhoe Broadcast News in July 2017.
Tell me a little bit about medical oncology?
Dr. Bendok: One thing we’re trying to do in health care, we’re moving from what I would consider conventional health care to individualized health care; where we try to predict and understand how a tumor is behaving. Not on average in the average patient. but in a specific patient. When we’re tackling a brain tumor for example it can be helpful to know where to expect to find brain tumor cells in addition to what you see on the MRI, in addition to what I would call the tip of the iceberg. With medical modeling it allows us to have a more intelligent approach to understanding where the tumor may be spread around the most concentrated area to try to ressect as much tumor possible which may give us a better outcome.
How does that work, how can you use math to do that?
Dr. Bendok: We use mathematics in everyday life to understand traffic patterns, storms, and you can actually medically model and predict the behavior of flowers, fruits, the growth of vegetables, crops etc. So the same way with tumors; tumors can be understood mathematically. And by understanding their equations or how they’re behaving, it puts us just one step ahead in terms of being able to understand where they’re spreading and how we can tackle them in a more specific manner.
It seems like the tumor would be less predictable, have less predictable growth than say a crop?
Dr. Bendok: True the equation is more complex. And so there are some simple equations. What we perceive as predictable in nature are things that have more simple equations. As it turns out even chaotic behavior, let’s say take the universe, stars and black holes, all those things fall in mathematical equations. Tumors in a way while they may seem to be unpredictable actually follow a pattern; it’s just a bit of a more complicated equation. And as it turns out, we can pretty accurately predict the rate of growth and where we would most likely find a tumor outside of the most obvious areas.
This must make whenever it finally comes to fruition … Seems like it would make your job much more accurate?
Dr. Bendok: If you think about the history of surgery, if we’re tackling a tumor surgically it relies on standard imaging, the experience of the surgeon and many, many years of training. But if we were to make it more accurate, in terms of understanding how the tumor is behaving and then tackle it in a way that’s very specific to the patient, I think it would make surgery more precise. In a way hopefully associated with better outcomes which are always gratifying for the surgeon and the team.
What does this mean in real life for the patient who has got brain tumor?
Dr. Bendok: If we take a step back and look at brain tumors, malignant brain tumors are essentially impossible to remove fully. The idea or the goal is to remove as many cells as possible to allow chemotherapy and radiation to work better. It’s been shown that the more tumor cells that are removed the better the outcome. Now that has a limit, because if there comes a point where if you remove too much tissue you could start to affect function. So we always trying to balance the length of life, maximum tumor resection with quality of life and that’s really an equation that we have to individualize for the patient.
How soon do you see something like this happening, math actually being a part of this?
Dr. Bendok: One of the steps towards allowing this kind of technology and this kind of approach to come into the OR is to enhance intraoperative imaging. Things like intraoperative MRI and even the concept of operating in an MR scanner. These are things that are being researched and advanced very quickly. I envision in the next five years we’re going to see quantum leaps in our ability to operate based on real time imaging in the OR. And I think that will be associated with better outcomes.
Tell me a little bit about the individualized mapping function and the awake surgery?
Dr. Bendok: Anytime we think about a brain tumor, unlike let’s say a liver tumor where we can cut out a big piece of the liver and not be as concerned about a specific body function, although there are limits to that as well. Anytime you’re operating in the brain you have to think about a person’s ability to move their arms or legs, perhaps their ability to conduct an interview or sing or to play a musical instrument. These things may be exquisitely important to the patient. We have actually gotten much better at mapping those functions using functional MRI. So we can actually generate a map of the brain that includes functions that are generally important, but also functions that are individualized to that patient. We’ve had some opera singers, some pianist and violin players where we actually map that function using MRI. Then we have them bring that instrument into the OR, or if they happen to be a journalist or a talk show host we actually have them conduct an interview or play a musical instrument in the OR to allow us to map the brain as we’re operating. We overlay the functional map with the tumor map and then the functional mathematical map with a big question of how can we take out as much tumor as possible without affecting function. And that’s a very important dimension of the whole operation.
The mathematical part would make that even more precise?
Dr. Bendok: Correct. It’s all about being strategic where you look. You want it to be as if you’re searching the ocean floor for remnants of the Titanic, you could sweep the entire Atlantic. On the other hand you could mathematically model based on a certain equation that included direction of the ship moving, speed and several other factors, wind perhaps. You factor all those things in and you come up with an equation, all of a sudden it gives the submarine a certain limited range. This happens a lot of times with airline crashes in terms of knowing where to look intelligently so that you’re not just doing a blind search. I think these sorts of things are how we try to approach a brain tumor operation in terms of trying to provide the patient with a safest approach. Because as you know we don’t want to be digging around in the brain unnecessarily and that seems obvious. We want to be very, very precise to look for areas that are high likely to have a tumor and low likelihood to have function. If you overlap a functional map that is studied both before surgery and in real time and you overlay that with a map that gives you the probability of finding the tumor in every cubic centimeter. There are some areas where we know for sure this is just tumor. But there areas where the tumor starts to blend with the brain and so we want to know what’s the return on investment so to speak. If we’re going to be resecting this piece of tissue ideally it would have lots of tumor and no function. Sometimes the lines get blurry and may have intermediate amount of tumor but maybe a touch of function. The question then becomes how much of that can we take safely. And that’s the equation we’re trying to tackle; it starts way before surgery when we study a patient’s brain with functional MRI. We map the brain and then we map it again in real time in the OR. For example, we can have a patient play the piano so we can see if that function is being affected. And that’s a very important part of the overall equation of optimizing the surgery to that patient’s life and quality of life and so on.
END OF INTERVIEW
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