[Please stand by for realtime captions]

Transcription

1 [Please stand by for realtime captions] >> Welcome to the American brain tumor Association, re-webinar series. Thank you for participating in today's webinar. Today's webinar is been graciously sponsored and is on whole brain radiation versus stereotactic radiosurgery. Dr. Steven Chang will be presenting. All lines during our webinar will be muted. If you have a question, type and submit using the question box in the control panel on the righthand side of your screen. Dr. Chang will answer questions at the end of his presentation. In the next few days, you will receive an asking you to take a brief survey to evaluate the webinar. Please take a few moments to share your feedback, which is important to plan for future webinars. This is being recorded and it will post to ABT's website on any time learning page shortly. Registered participants will receive the recording link in a follow-up message tomorrow. Let's begin our webinar recording here. >> The American brain tumor Association is pleased to welcome you to the webinar series. Our webinar will discuss whole brain radiation, versus stereotactic radiosurgery. My name is Christine daily, program manager here at the American brain tumor Association. I am delighted to introduce our speaker, Dr. Steven Chang. Dr. Chang is a professor and vice chairman of the strategic development and innovation in the Department of neurosurgery at Stanford. He is also the inaugural holder of the Robert and Jeanette Powell professorship in the neurosciences at Stanford University school of medicine. He has a national and international reputation as a next word in both her surgery and radiosurgery for treatment of rain, spine, and school-based tumors. He is the codirector of the neuro-oncology program. His radiosurgery part practice focuses on the CyberKnife to treat parts of the Spain -- spine and brain. He was instrumental in the CyberKnife program and is codirector of the program currently. Thank you for joining us Dr. Chang, you may not be in your presentation. -- You may now begin your presentation. >> Good morning. I would like to thank the American brain tumor Association for this opportunity to speak on whole brain radiation and stereotactic radiosurgery. I am going to provide a broad overview of these two modalities, as well as the advantages and as a vestiges of each. I will be happy to answer questions at the end of my presentation. >> What is whole brain radiation therapy? I would like to start with some definitions of what these two types of radiation are. They can be confusing when patients hear the word radiation, it is a very generalized term. Let's start with definitions. Whole brain radiation is a long-standing method of delivering radiation to cover the entire brain, and this type of radiation treatment has been around for 60 to 75 years and it is primarily used to treat brain metastases tumors because those are the type of tumors that will be dispersed through the entire brain. Whole brain radiation is not used to treat very localized tumors such as meningiomas or [Indiscernible]. We will discuss this in more detail later. How does whole brain radiation work? It works by giving small doses of radiation through the entire brain on a daily basis. In this case, the patient would come in to the medical center for anywhere from two to six weeks to receive radiation for their type of tumor. Whole brain radiation does not require any targeting of accuracy. You are treating the entire head. One question that comes up is, how do the normal healthy brain tissues, how do the neurons in the brain tolerate this type of treatment? In this case, what we are utilizing is the fact that normal healthy rain sells -- brain cells are better at repairing radiation cells than other cells. Essentially, the normal healthy brain cells receive the same dose of radiation as tumor, but over the next four hour period between the first radiation dose and the second radiation dose, the normal healthy brain cells have a series of repair mechanisms that occur in each cell that correct the damage from the radiation. The tumor cells also attempt to correct the damage of the radiation, but

2 they are not as effective as the normal cells. So essentially, the normal brain cells are better able to tolerate the radiation and the tumor cells are more sensitive to the radiation and therefore are more likely to be damaged by this type of radiation. >> In terms of source of radiation, I have a couple of slides on machine types. You'll often hear the word linear accelerator. It is abbreviated LINAC. A linear accelerator is a machine that generates x-ray photons. X-rays are the same type of radiation that we use on a mammogram or chest x-ray, but then utilizing them to treat tumors, we use higher doses of these x-ray taunts to destroy the tumors -- photons to destroy the tumors rather than [Indiscernible] down the machine and they strike a metal target, typically it is tungsten, and this collision between electrons and the metals create x-ray beams which are then targeted to the patient. This is a picture of a standard linear accelerator. The patient is lying on a table and the machine itself can rotate around and access on the wall. And the table itself can rotate on the ground, which is called the turntable rotation. This type of linear accelerator has been utilized for many decades. The machine itself has not changed much over time. >> When should whole brain radiation be used? There are several instances in which this type of radiation is the preferred therapy. The first situation where we like to recommend whole brain radiation is when there are multiple brain tumors, and this is a vague term because what constitutes multiple varies from center to center, but for example, the patient showed up with 30 brain metastasis in their heads, we would recommend whole brain radiation has of the sheer number -- because of the sheer number of tumors to be treated. When you have that many, it is not practical or feasible to do surgery or do focused radiosurgery to treat those types of tumors. >> The second incident where whole brain radiation might be used is when there is a high suspicion that there are additional tumors in the brain that are not visible on the patient's current MRI scans. What does this mean? It means when we look at the MRI scan and identify the tumors, we are relying on the fact that the tumors are of a certain size or number of cells to make them visible on the MRI scan. By the time a tumor is visible on the scan as a small dot or image, it is tens of thousands of tumor cells. If we look at a smaller number of tumor cells, let's say 1000 or 5000, that particular tumor will be too small for us to see on the MRI scan. It would be impossible to target those relatively invisible tumors with a focused radiation, such as radiosurgery, but very easy to target with whole brain radiation because essentially whole brain radiation is covering the entire head and therefore anything visible or not would be treated. Whole brain radiation is also used when the type of tumor that you are attempting to treat is very sensitive to radiation. That means the tumor cells respond and die very quickly to doses of radiation. Breast cancer, rest metastasis to the brain, lung tumors that go to the brain are tumors that are very sensitive to radiation. Those type of tumors would be a consideration for whole brain radiation. This is an example of the patient's MRI scan of the brain. It is one representative slice. The brain is the gray material and you can see on just this one slice, this patient has a number of tumors that are shown in white. Some are larger than others, some are very tiny white dots. This is a patient where we would consider whole brain radiation because of the large number of tumors hasn't. >> Furthermore, when you see this many tumors, it is likely that there are additional tumors that are too small to be seen by the MRI scan, but are present. Those would also get covered if this patient underwent whole brain radiation. >> When should whole brain radiation not be used? Again, this is not set in stone, but these are guidelines. In general, if there are a few tumors, let us say the tumor this patient shows up with -- let us

3 say the patient shows up with only one or two on the brain scan, we would not recommend whole brain radiation and we we can that are using a focused radiation in the warm of radiosurgery. The reason for this -- in the form of radiosurgery. It is difficult to make the argument that you should radiate the entire brain, all of the healthy neurons of the brain, in an attempt to treat just one or two tumors that are visible. In this case, we would recommend to this patient that had one or two tumors to consider radiosurgery rather than brain radio -- radiation. Another situation in which whole brain radiation is typically not used are for tumors that are highly resistant to radiation. What does this mean? As I mentioned in the previous slide, that breast and lung cancer tumors are very sensitive to radiation, there are other tumor types such as melanoma that are highly resistant to radiation and take higher doses of radiation to kill. In these tumor pathology types, we typically like to treat these with focused stereotactic radiosurgery, in which we can deliver higher doses of radiation to those tumors. Patients who have had prior whole brain radiation, we usually do not recommend a second course of whole brain radiation. It is very rare that we would do that. The reason for that is that again, with whole brain radiation, the normal brain tissue has received a fairly substantial dose of radiation already in the past and any additional radiation to that normal tissue may result in increasing levels of complications. >> The last situation which we typically don't start off with whole brain radiation, is when the patient's MRI scan shows an enlarged tumor causing mass effect. This is an example of a large tumor causing mass effect. You can see the tumor as the large white mass and around the tumor you can see a dark gray area and the normal brain is shown as a lighter gray area. The dark gray area represents edema or swelling or in this case fluid in the brain tissue as a result of this large tumor pushing on the brain. In this situation, we would advocate surgical resection first prior to any radiation being used. If you treated this patient with whole brain radiation, you might run into problems with worsening swelling around the tumor during the radiation treatment. >> The advantages of whole brain radiation, all tumors in the brain both visible on the MRI scan and nonvisible will be treated. There is no chance of missing a small tumor that is below the resolution of the MRI scan. Whole brain radiation is an outpatient treatment and even though it may be [Indiscernible] they typically come in each day for their treatment and leaves and comes back home. Whole brain radiation is utilizing the linear accelerators that are common among medical centers and can be even done at smaller facilities because these are common types of radiation machines. >> The disadvantages of whole brain radiation that I want to cover, the first disadvantage is that it may disrupt systemic treatment. Patients with cancer are often on chemotherapy treatment delivered by their medical oncologist. If the -- if a patient is undergoing whole brain radiation therapy, they often have to stop there chemotherapy treatment for the period of time that the patient is actually receiving radiation. If the patient is receiving radiation or three weeks for their breast cancer tumor that has spread to the brain, we would have the medical oncologist stop any chemotherapy for that three-week period of time. This can sometimes cause a disruption because the patient is receiving there chemotherapy because of their cancer disease and so there is a lot of reluctance on the part of the patient and the oncologist in terms of withholding that treatment for a period of time. Whole brain radiation require several weeks of treatment to deliver. It is typically Monday through Friday, five treatments a week, and so if a patient requires 15 treatments, you're talking about three weeks of treatment to complete this course. Whole brain radiation has some side effects. Generally there can be some fatigue and this is something that starts during the later part of the course of radiation. It is not immediate. Towards the tail end, fatigue can kick in and can last for a number of weeks after the

4 treatment is completed. It is generally self imitating and resolves on its own. Whole brain radiation results in temporary hair loss, though the hair will thin and fallout in clumps and it takes some period of time to grow back. There can be some hearing loss that can occur with whole brain radiation. Not immediately after treatment, but down the loss and that is -- down the line and that is because the region of the cochlea are sensitive to radiation and after whole brain radiation treatment, a year or two later, patients may develop some decrease in hearing because of this. Balance problems can occur over time after ABT, and this is due to the attack on the cerebellum, the area of the brain that controls balance and coordination. It is also similar to the hearing region of the brain. >> Finally, the most in side effect of whole brain radiation is that patients worry about their cognitive ability. Their memory and their concentration. This is something that is not necessarily happen right away after whole brain radiation, but once a patient reaches one year or two years after, a substantial percentage of these patients will exhibit memory and concentration difficulties. It is a side effect that patients worry about because it can impact the quality of life and it is somewhat of a trade-off because we are attempting to kill the tumors in the brain now in the present and we accept the fact that there could be a risk of cognitive issues down the line. >> I want to switch gears now and talk about stereotactic radiosurgery. The word stereotactic radiosurgery, what does that mean? Stereotactic is a word that means a method of delivering highly focused beams of radiation. So stereotactic uses a three dimensional ordinance system to deliver radiation precisely to the brain or any other part of the body. Radiosurgery is the word that combines the use of radiation with the precision of surgery. So radiosurgery is the generic term for a variety of machines they can deliver highly focused beams of radiation to their targets. I described this to my patients as the beams are like laser beams. They are very precise and they target the tumor and a spare the normal brain tissue around the tumor. It is highly effective for many brain tumors as a treatment. In many cases, it is an alternative for open surgery for these brain tumors. Radiosurgery was developed not by a radiation position, it was developed by neurosurgeons. It was conceptually thought of as a surgical procedure as an alternative to open surgery in the operating room. >> How does stereotactic radiosurgery work? As mentioned previously, it is a method of delivering highly focused beams of radiation to the target, in this case the target is a brain tumor. The accuracy is within 0.51 millimeters, so this is roughly 1/25 to 1/50 of an inch. That is how precise the radiation can be delivered. Multiple beams of these precise radiation beams are targeted on the tumor to deliver the lethal dose to the tumor. Because of the position of delivering the radiation, there is essential -- essentially limited damage to surrounding tissue. The vast majority of the neurons are spared from radiation when delivering this type of treatment. >> This is an example of a radio surgical treatment plan. In the upper left image you will see almost a cartoon picture of the patient's head. You can see the eyes and nose and mouth. Then you will see some light blue lines. Each one is a beam of radiation. You can see they are coming into the head for many different angles. They all seem to be pointing at a single spot in the patient's left for head. If you look at the other three images on the screen, those are MRI scans and you can see the location of the brain tumor that is being delivered with this focused beam of radiation. If you look carefully, you can see a series of colored lines around the brain tumor and that is the rapid fallout of radiation at the margin of brain tumor, see you can see there's not really any substantial radiation dose going to the rest of the brain tissue.

5 >> When should radiosurgery be used in patients? Again, there is not a black-and-white set of rules. The general concepts I will discuss, but there can be some variability from center to center. The first instance where we would recommend or consider using stereotactic radiosurgery is when there are just one or a few tumors. As you recall with whole brain radiation, we utilized it when there were many tumors. Radiosurgery can be utilized when there are just one or a few tumors, so in the previous slide, this patient had one tumor. Rather than radiating the entire head and exposing the entire brain to radiation, a focused radiation treatment make sense. >> A second situation in which radiosurgery can be used is when the systemic chemotherapy treatment is not recommended to be interrupted. As you recall with whole brain radiation, if it was delivered for three weeks, we had to stop the chemotherapy. In the course of radiosurgery, in which the radiation can be delivered in a single day, instead of three weeks, it makes it more feasible for the patient -- the patients in colleges to continue treatments without any interrupt -- interruption. >> The third way to use this is when the tumor type is resistant to radiation. I use the example before of melanomas. These tumors do not respond well to low doses of frequent radiations that are given with whole brain radiation therapy. They do respond very well to single high doses of radiation that are typically used with radiosurgery. In the situation, with melanoma, we typically avoid whole brain radiation and we do radiosurgery for these patients. Finally, there are some patient who come in with five or six or seven brain tumors and they are right in that gray zone between whole brain radiation and radiosurgery. In some cases they feel strongly that they want to avoid the cognitive side effects of whole brain radiation and so they want to go with radiosurgery, even though they know there may be tumors that are not quite visible yet on the MRI scan that may manifest themselves later. >> When should radiosurgery not be used? Again, there are no hard and fast rules but just guidelines. The first is the tumors are large and causing a massive effect on the brain. If you remember the slide earlier showing that large tumor with pressure on the brain, that would not be a good candidate for either whole brain radiation or radiosurgery. They should have surgical resection before considering any form of radiation. In tumors that are highly symptomatic, let's say you have a tumor that is pushing on the brain and it is impacting your balance or your speech function, radiosurgery is often not the best first-line treatment because the goal of treatment is to take the pressure off of the brain to alleviate the patient's symptoms and hence, surgery may be the initial modality. Also if there are -- is significant swelling around the tumor prior to any treatment, we often rethink the role of radiosurgery. The reason is that radiosurgery can actually make swelling around tumor temporarily worse before the tumor dies and the swelling gets better. If a patient comes in with significant headaches teachers related to swelling -- seizures related to swelling around the tumor, you need to be prepared for the swelling to get worse if you do surgery before it gets better. Last, if there are many tumors or concern there are tumors that are not visible on the scan, then we typically do not recommend a focused beam of radiation with radiosurgery. We consider whole brain radiation instead. >> Here is an example of a situation where we might not want to treat with radiosurgery. This is the patient's MRI scan. You can see the tumor in the top of the brain and on the sequence, this is with contrast that was injected into the IV when they patient was in the scanner, so it lights up with the contrast dye. On the scan, you cannot appreciate any swelling around the tumor, but there are different sequences where you can obtain that. In the sequence, the large white area is actually swelling in the normal brain around this particular tumor. Looking at the scan, we would identify correctly that the

6 patient does have a brain tumor but we would also appreciate the fact that this tumor is causing a significant amount of brain swelling and any type of radiation, whether whole brain radiation or focused radiation, is likely to make the swelling worse. If this patient already presents with symptoms, such as severe headache or cognitive problems or seizures from all the swelling, radiation is likely to make that worse, at least in the near term before the tumor dies. >> This is another situation in which we would not recommend use of radiosurgery. This is a tumor that is causing significant mass effect on the brain. In this situation, the tumor is located deep in the center of the brain and is pushing on the brainstem, which is adjacent to the tumor. This person is likely to have significant problems with walking or the strength in their arms and legs because the tumor is squashing a part of the brain that connects the brain and the spinal word. Radiating this tumor is not likely to decompress the brain very quickly and this patient should have surgery first. I showed you examples in which we would not use radiosurgery, but what are the advantages of radiosurgery in patients where you can use it? These are some examples. I can describe them in more detail. The first advantage of radiosurgery is that it minimizes radiation to normal brain tissue, and again this is highly focused radiation, it can target the tumor with high precision and spare the normal brain tissue. On an actual tumor by tumor basis, radiosurgery has a higher chance of killing a tumor that whole brain radiation because a single high dose of radiation typically works better at killing it tumor that many smaller doses of radiation. Radiosurgery is also an outpatient treatment and can be done fairly quickly. It does not interrupt the chemotherapy cycles that we previously discussed. Unlike whole brain radiation, which is typically delivered once over the patient's lifetime, radiosurgery can be repeated multiple times. For example, the patient shows up with a single brain metastasis from their lung cancer and retreated in July 2018, and they develop two more tumors in December 2018, we can repeat radiosurgery again and we can repeated again in 2019 if they were to develop more. It is not uncommon for a patient undergoing radiosurgery with multiple brain tumors, let's say from their lung or breast cancer, to have many courses of radiosurgery over the course of their lifetime. It is not uncommon to treat 25 or 30 tumors over the lifetime of the patient with radiosurgery. >> The primary advantage of radiosurgery is that it can be delivered in one or a few treatment, one or two days of treatment, rather than 15 or more days with whole brain radiation. Lastly, the radiosurgery generally avoids cognitive side effects of whole brain radiation, so the memory issues, the forgetfulness, that we see a year or two after whole brain radiation is not something that we see with stereotactic radiosurgery. >> Here is an example of a patient that we treated at Stanford 20 years ago. This was on the CyberKnife machine. You can see the slide to the left, the patient has a medium sized tumor in their region of the brain called the temporal lobe. The tumor is shown by the purple arrow and the edge of the tumor is outlined in white. This patient underwent stereotactic radiosurgery and you can see two years later, it is almost impossible to see where that tumor was. The purple arrow on the right image is showing where the tumor was. The tumor has shrunk dramatically and essentially disappeared on this patient's scan. >> What are the disadvantages of radiosurgery? The first disadvantage is radiosurgery can only target tumors that you can actually see on the MRI scan. We talked previously about small tumors that are below the resolution of the MRI scan. Those tumors would not be seen on the MRI scan and therefore cannot be targeted with radiosurgery, and therefore would be missed. Typically after you do radiosurgery, you obtain periodic brain MRI scans on the patient, let's say every three months or so, and

7 if there was a tumor that was not visible on the MRI scan on the present day, it may be visible three months from now, in which case you could treat it with radiosurgery at that point. Another disadvantage of radiosurgery that we already discussed is that it can make swelling around the tumor temporarily worse, and this can increase [Indiscernible]. If the patient has never swelling in the brain around the tumor that is causing arm or leg weakness and the patient underwent radiosurgery, you would need to prepare that patient for the consideration of that weakness possibly getting worse for the next few months before it would get better as the tumor dies. The other disadvantage is that these tend to be more complex machines than the standard radiation machines, and not all facilities have these higherlevel radiosurgery machines. It may mean you may need to travel a further distance to receive this treatment than you would for whole brain radiation. >> There are many radiosurgery machines and I want to explain them briefly here. We talk about a transects -- transects to develop whole brain radiation. The type we utilize and Stanford is the CyberKnife. Cyber meaning computer and knife meaning a surgical tool, so it is a way to deliver focused radiation to tumors. It is made by a company, which is based in Sunnyvale California. It is a large medical device company which makes radiation machines and they are also based in the sense -- San Francisco Bay area. They make true beams and trilogy machines. We have those at Stanford. Those can also be used to deliver radiosurgery in patients. Brain lab is another company that makes a machine that delivers radiosurgery. Those are all linear accelerator machines that use x-ray photons to treat tumors. Another popular radiosurgery machine is called the gamma knife. This was developed back in the 1960s, so it has been around for a while. It uses radioactive cobalt to generate gamma rays to deliver the radiation dose. Finally, a proton beam is a form of radiation that can be used to treat brain tumors. -- You will sometimes hear of these obsessive there are number across the U.S. and they can be used to do radiosurgery, as well. All of these types of machines, the proton beams, gamma knife, LINAC, all use a dose of radiation to kill a tumor. To some extent, the source of the radiation is less important than the dose, and with the brain tumor sees is just a specific dose of radiation. The brain tumor does not know the source of the radiation or the type of machine that is used to deliver it. >> Here is what we covered. Gamma knife uses gamma photons. The proton beam uses accelerated protons. These all deliver the radiation to the tumors and the tumor does not know the source of the radiation. It just sees the dose. Similar to whole brain radiation when you do radiosurgery, the method is electrons hits a metal target and collision based x-ray beams can be focused to target the patient. Here is a schematic and this is the only physics slide I will show, so don't worry about the complexity. Essentially, x-ray beams -- the electron beam is delivered down the tube and it strikes a metal plate and it generates the x-ray photon, which is the blue line which is then delivered to the patient. With the gamma knife, it uses radioactive cobalt as the source of radiation and this radiation source, like any other radioactive material, is always on and is kept behind the lead shield were not being utilized. Small openings in the lead shield during treatment are open and this allows the radiation to come out to treat the patient. Proton beams, they accelerate the particles to very high speeds and patient is treated on the treatment table by these high-speed protons that are delivered at various different angles. >> I want to show a couple of slides on this machine that I am familiar with. This is a lightweight LINAC and delivers beams by moving around the patient. This is what the cybernetic machine looks like. The linear accelerator is mounted onto a robotic arm and this is a cartoon of what a treatment looks like. The flat surface is where the patient lies on the table and you can see two cameras in the ceiling taking images of the patient during the treatment.

8 >> I want to conclude with talking about situations where we would combine different treatment types. We have talked about whole brain radiation is a treatment totality, we have talked about stereo tech radiosurgery -- stereotactic radiosurgery is a indiscernible Mac -- [Indiscernible] here is a situation where we might combine the two treatments. Let's say a patient shows up with MRI scans of their brain shows 30 different or 40 different brain tumors. We would recommend that patients start off with whole brain radiation therapy. Let's say the patient receives the treatment and their next MRI scan three months later shows that of the 30 tumors, 28 look like they are shrinking, but two are still expanding. You could then use focused radiosurgery to finish off those two remaining tumors that look like they are still viable after the treatment. >> Another situation is let's say a patient comes in and they have just one or two tumors and you do radiosurgery on them and kill those tumors. Let's say their disease progresses over time and the following year they now show up with an MRI scan that shows many many tumors. At that point, you can add the whole brain radiation therapy to treat those multiple tumors. I mentioned there are situations where we would combine whole brain radiation and radiosurgery with conventional surgery in the operating room. The first example would be a single large tumor and many small tumors. This patient has five or six or 20 tumors, let's say. One is very large and the rest of the tumors are tiny. It may make sense to do surgery to remove the large tumor first and then use whole brain radiation to treat the brain to get the smaller tumors. Another situation where you would combine radiosurgery and surgery is let's say there are just two tumors, one is large and causing swelling and symptoms, the other one a small and not causing any problems at all. You may recommend surgery to remove a large tumor to alleviate the patient's clinical symptoms and then radiosurgery to treat the small tumor that is on the other side of the brain. >> To summarize, I wanted to explain today and hopefully I did that whole brain radiation and radiosurgery are both tools that we used to treat brain tumors. They each have advantages and disadvantages. And it is not whole brain radiation versus stereotactic radiosurgery, they are both tools that we can use to treat brain tumors. The optimal use and timing of whole brain radiation therapy and radiosurgery is individualized for each patient. As I mentioned, these guidelines that I covered today are not set in stone. They are very individualized from patient to patient. That is the reason that patients undergo specific formal evaluations in clinic prior to determining the course of radiation treatment. Last, whole brain radiation and radiosurgery are just one of the key modalities in the treatments of patients with cancer, along with surgery and chemotherapy. It is not a radiation versus surgery argument. What we like to do is consider all of these options for patients and come up with the best option for each individual patient, even if it means combining treatments. Obviously, it is not just me doing this type of work, there is a whole list of individuals and they are shown here, including other neurosurgeons, ecologists, physicists, as well as radiation therapists and schedulers. I would like to thank you for your time and attention today. I would be happy to answer any questions that you may have. >> Thank you Dr. Chang. We will now take questions. If you have a question, please type and submit it using the question box in the webinar control panel on the right-hand side of your screen. Our first question for the day is, and radiosurgery -- can radiosurgery be used on the same tumor quacks -- quacks >> Yes, it can. When delivering radiation to a tumor, there is never 100% guarantee that the tumor will die. The success rates are quite high. Typically, they are above 90 to 95% chance of killing tumors with

9 radiosurgery, but in the off chance that the tumor continues to progress despite surgery, you can do a second course of radiosurgery to the same tumor. >> Question -- the next question is, why should whole brain radiation not be utilized if it has been used before? >> That it -- is a good question. The answer is that the dose of radiation used for whole brain radiation is fairly close to the upper limit of what a normal brain can tolerate before we see high amounts of side effects. If you were to deliver a second course of whole brain radiation, you would be essentially almost exceeding the normal brain tolerance to radiation, and so the side effects first of all, would be highly likely to occur and second of all, be highly significant in terms of their clinical significance. A patient is likely to have a lot of deficits with cognitive issues with a second course of whole brain radiation. >> Thank you. Next, are the various types of SRS radiation time, gamma, x-ray, equally effective on all type -- types of tumor or do some radiation types work better on specific tumors? >> The answer to that for the most part is that the choice of the machine is less important in killing the radiation than the dose of the radiation utilized. What does that mean? That means that in each of these machines, you can choose dial-up, or you can dial down the dose of the radiation. The tumor only sees the dose of radiation it is given, does not see the source. When I explained this to my patients, I use the example, if a tumor is an egg in a boiling pot of water, with the axes is a certain temperature -- egg sees is a certain temperature. It does not know if it is a gas or electric stove. It only sees the temperature. 250 degrees Fahrenheit, for example. It does not know the source of the heat, so for the tumors, they only see the given dose of radiation. They do not know if it is coming from a gamma knife or a CyberKnife, so therefore it is not the machine that is effective, it is the choice of the radiation dose used. >> Okay. The next question, do you have any recommendations for patients in helping them to manage the fatigue or any of the other side effects they experience from the whole brain radiation? >> So the question is managing side effects from whole brain radiation. Fatigue was brought up as one of the side effects. Generally, that is something that is self-limiting. It lasts anywhere from a few weeks to a few months and it gets better over time. Generally, that does not require any medical intervention to resolve. In terms of the cognitive side effects, that can be difficult to manage because those tend to be gradual in onset and progressive overtime, meaning they are likely to worsen as time goes on, even though the radiation treatment was done months or years ago. This cognitive side effects can substantially impact quality of life. People have tried various things, they have tried medications that maybe would essentially be a stimulant for the patient, but again, you are then adding medications to a list of possible other medications that the patients are on. It is difficult to manage the cognitive side of X with medication. -- Side effects with medication. We recommend lifestyle meant -- modification rather than -- coming up with an organizational system, visual aids, reminders, those are situations where we would try to manage that. >> Next question, is stereotactic radiosurgery approved for pediatric patients quacks >> Yes.

10 >> Is there any difference in the accuracy and effectiveness between a proton beam and other forms of SRS, for example gamma knife? >> That is a question that comes up commonly and the challenge here is there is often times not a lot of published data in the medical literature regarding accuracy of the machines. The machine vendors will often try to promote or site targeting accuracy, but in the medical field, it needs to be published in what we call a peer reviewed evaluation, so it needs to be tested and validated and reviewed by third-party reviewers for to be considered a legitimate targeting accuracy. With machines like Gamma knife and CyberKnife, there have been published accuracy around 0.5 two 0.6 millimeters, and so that is published data on the machines that are used commonly. For machines like protons, their use not just for radiosurgery but other types and forms of radiation. There is not that level of published literature. >> Thank you Dr. Chang. That is all the time we have for today. Thank you all for joining us and thank you Dr. Chang for this wonderful webinar presentation. Besides our free educational webinars, ABTA has a variety of webinars available to help connect patients and caregivers to help connect and support them in their brain care journey. For more information, you can visit ABTA's website and you can call their Caroline at Let us pause for just a moment to conclude our recording. We invite you to check back at our website A library of free webinars addressing a wide range of brain tumor topics, from treatment options to quality of life and management. Concludes our webinar. Thank you for joining us and please be sure to complete the evaluation you will receive by within the next two days. You may now disconnect.