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Radiation therapy is a treatment that uses X-rays to kill cancer cells. Join radiation oncologist Sudha Amarnath, MD as she discusses how this therapy can be used to treat colon and rectal cancer, the different types of radiation therapy, and what a patient can expect during these sessions.

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Treating Colorectal Cancer with Radiation Therapy

Podcast Transcript

Scott Steele: Butts & Guts, a Cleveland Clinic podcast exploring your digestive and surgical health from end to end.

So hi everybody, and welcome back to another episode of Butts & Guts. I'm your host Scott Steele, the Chairman of Colorectal Surgery here at the Cleveland Clinic in beautiful Cleveland, Ohio.

And very pleased to have her second appearance on Butts & Guts, last joined us in 2019 to discuss the long-term side effects of cancer treatment, so kind of the negative side. But we have Dr. Sudha Amarnath, who is a radiation oncologist here at the Cleveland Clinic in our Taussig Cancer Center, and one of our lead radiation oncologists for both colon and rectal and anal cancer as well. So Sudha, welcome back to Butts & Guts.

Sudha Amarnath: Thanks for having me, Scott.

Scott Steele: So for those of the listeners who have not listened to your original one, give us a little bit of background about you. Where are you from? Where'd you train? How'd it come to the point that you're here at the Cleveland Clinic?

Sudha Amarnath: I was born and raised in beautiful Lansing, Michigan. So, go Blue, even though I know it's Michigan State territory. I went to the University of Michigan for medical school so I have some mixed allegiances there. But I grew up in Lansing. I ended up studying chemical engineering and biology at the Massachusetts Institute of Technology. And then, as I mentioned, went to medical school at the University of Michigan.

Decided to kind of broaden my horizons by moving to the west coast, which is where I did my radiation oncology training at the University of Washington. And then, wanted to be a little bit closer to home and join this world-class institution. And so I was really excited when there was a job opening at the Cleveland Clinic, and I've been here for the last seven years now.

Scott Steele: Well, we are lucky to have you. And so let's start off with just a high level overview. What is radiation therapy, and how does it fit into the role of treatment for cancers?

Sudha Amarnath: Yeah. So radiation therapy is one of the three tools that we really think about when we're thinking about the care of a patient who has a new cancer diagnosis. And so the other two tools are ones that I think most patients are often more familiar with, which are surgery and chemotherapy. But radiation has actually been used for cancer treatment since really the late 1800s, early 1900s, so it's one of the oldest therapies that we know is effective against cancers.

Radiation in the modern era works in combination with chemo and surgery to really treat patients for a number of different cancers. It can be used to treat a cancer, basically with what we call curative intent, which means that the radiation is actually one of the main treatments that gets rid of the cancer without necessarily the need for surgery. It can be used before or after surgery. What we call either neoadjuvant or adjuvant therapy to kind of complement our colleagues in surgery who remove cancers.

And it can also be used palliatively, basically to help with symptoms that can be related to a cancer, things like bleeding and pain. And so radiation actually plays a really large role in the care of cancer patients, and almost 60 to 70% of patients who have a cancer diagnosis will end up getting radiation at some point during their course of therapy. But it is one of the three tools that we use in the care of many cancer patients.

Scott Steele: Sudha, broad strokes: what's the difference between radiology and getting a CAT scan or an MRI or something like that, and then radiation therapy?

Sudha Amarnath: That's a great question. That's one that often confuses a lot of our patients. But both radiology and radiation therapy use radiation, an ionizing radiation, to basically do what we do. And so on the radiology side, it's also known as diagnostic radiology, and those are the people who really take images or pictures of patients so that we can get a better sense of what's going on inside of them. And it's called diagnostic radiology because we use those images primarily for diagnosis.

On the radiation therapy side, we use radiation in a therapeutic setting. So we're essentially using radiation to kill cancer cells. And that's why we're called radiation oncologists, because primarily that's where therapeutic radiation is used, is in the treatment of cancer.

Scott Steele: So I know that you have an extensive background in terms of anal cancer as well as GYN cancers. We're going to specifically focus today on colon and rectal cancer. So let's separate those two, they often get clumped together. So why would I be recommended to have radiation therapy instead of other treatments or in conjunction for other treatments, such as chemotherapy and surgery, like you talked about, for rectal cancer? And then is there a role for radiation therapy in colon cancer?

Sudha Amarnath: So these are great questions and I'm lucky to work at an institution with people like Dr. Steele to really deliver multidisciplinary care to our patients with rectal cancers, and sometimes colon cancers. In rectal cancer, radiation plays a really big role. And as Dr. Steele could describe more vividly than I can, the anatomy of the pelvis, which is where the rectum is located, is a little bit different than the abdomen where the colon is located.

And so sometimes it's harder for our surgeons to get into those deep spaces and ultimately prevent all of the cancer from coming back in the future. Because the spaces are really tight, there's a lot of lymph node groups that live in the pelvis area that are at risk of harboring cancer cells when someone has a rectal cancer that's a little bit more what we call locally advanced.

And so ultimately radiation can play a really big role in helping to sterilize cancer cells that live in the pelvis that are harder for our surgeons to access. And also help assist our surgeons in getting what we call negative margins, which basically means that we're able to remove cancer fully without leaving any microscopic cancer cells behind, which is really important in preventing a cancer from coming back in our rectal cancer patients.

So radiation plays a really big role there, as opposed to colon cancer. In colon cancer, typically because of the way that the anatomy is, ultimately our surgeons are a little bit more easily able to get what we call wide margins around the cancer. And so the radiation often plays less of a role in that area because the spaces are a little bit easier for our surgeons to remove the cancer. So there's sometimes a role for radiation. if a cancer is sticking up to an area where it's harder for our surgeons to get those negative margins, like up against the abdominal wall or something like that, but typically much less of a role in colon cancer than for rectal cancer.

Scott Steele: So one of the things we would like to do here on Butts & Guts is to give patients a little bit of insight as to what to expect, and specifically as it relates to cancer. Sometimes when we're talking to them and they hear that cancer word, things get confusing. So what can a patient expect when they come to see you come to the Cleveland Clinic for radiation therapy? And maybe, what's the difference between getting treated versus simulation?

Sudha Amarnath: Basically, I kind of like to walk through the pathway that patients will go through. Because not only patients, actually, a lot of our colleagues in other disciplines have never spent time in a radiation oncology department. So I think it's helpful for other physicians as well to walk through this process.

So basically what ends up happening for most cancer patients is that they often meet a surgeon or a medical oncologist first. That person often will meet them, take their history and bring them to a tumor board discussion. And so Dr. Steele and I work very closely in these tumor boards to discuss patients. We talk about their imaging, we talk about their pathology, and figure out what's the most appropriate care and management strategy for each patient.

If a patient is deemed appropriate for radiation, then they'll come to see us in consultation. Where we'll talk through what radiation is, which is basically high energy x-rays that are used to treat their cancer, and how it's given, oftentimes in combination with chemotherapy. And once we've gone through a really informed discussion, they decide whether they would like to proceed or not.

And then the first step, if they've decided to proceed with therapy, is to do something called a simulation. And a simulation is basically kind of a dry run of what their radiation treatment will look like. So it's typically a CAT scan that's done in our department, and we make special immobilization devices so that a patient is essentially kept in the same position. Because radiation treatment is typically delivered over the course of several weeks, so it's a daily treatment Monday through Friday.

In the setting of rectal cancer, we usually are giving that over the course of about five to five and a half weeks. And so we want to make sure that the radiation is going only where it's supposed to and not hitting a lot of the normal tissues that we want to avoid treating with the radiation. So that simulation allows us to really come up with a setup for that patient that is reproducible and ultimately is a comfortable position that they're going to be able to stay in for those 25 to 28 treatments that they'll be going through daily.

At that visit, they usually will drink some contrast dye. We usually give them some IV contrast, so similar to what they may have experienced when they've gotten a diagnostic CAT scan. And the one big difference is that they also typically get three little tiny tattoos at the time of that simulation. Those tattoos are really tiny, they're about the size of a freckle. But those tattoos help our radiation therapists, who are the ones who deliver the radiation on a daily basis, to set patients up really accurately and precisely using laser beams.

So that's the simulation process. After they go through simulation, most patients will get about a week off. That's when we do all of our work of mapping and planning out the radiation and doing all of our safety and quality checks to make sure that our radiation plans are really individually tailored for each patient and safe.

And then the patient starts their radiation treatment. And the radiation treatment typically takes about 10 to 15 minutes on a daily basis, so it's not a long treatment. And most of that time is really spent making sure that the patient is in the correct position. The radiation treatment itself is only on for a couple of minutes during that whole process. And that's the only time that the patient's actually exposed to radiation.

So a lot of times patients will ask, will I be radioactive after I finished my treatment? Is it safe for me to be around other family members or babies? And the answer is yes to all of those questions. Because the radiation is basically a very high energy x-ray that's coming in, it's causing damage to those cancer cells. And then once the radiation machine, which is called a linear accelerator, is turned off, there is no further radiation. So that damage has been done to the cell, but the radiation does not stay inside of the patient's body. So they're safe to interact with anyone around them.

Scott Steele: Sudha, one of the other things that comes up is people get lost in some of the terminology, as it relates to radiation therapy. What is this whole, IMRT versus SBRT versus gamma knife or stereotactic knife, what is all this stuff? Can you give us the overview of it?

Sudha Amarnath: Radiation, just like chemotherapy or surgery, there's a lot of different techniques that we can use. And so they're all kind of just different tools that are in our toolbox when we treat a patient with radiation. And so it does get very confusing, but at the end of the day, your radiation oncologist will look at where a tumor is located and then decide which is the most appropriate tool to use.

And so when we talk about something like IMRT, that stands for intensity modulated radiation therapy. And basically, that's a technological advance that came about in the 90s and early 2000s, where we're basically able to more precisely plan radiation treatments to really avoid more normal tissues and really target the tumor more accurately. When we use intensity modulated radiation, we're still trying to treat usually a little bit of a broader range of tissue.

So in the setting of rectal cancer, we might use intensity modulated radiation therapy for a patient who needs preoperative radiation before surgery. And in those cases, we're treating where the cancer started in the rectum. We're also treating the meso-rectum, which is the fat space surrounding the rectum. That's where a lot of those little lymph nodes live. And then we also treat some of the pelvic lymph nodes.

So we're treating a little bit of a broader area within the pelvis, but we want to avoid things like the bladder and the small intestine, and intensity modulated radiation often helps us to shape things so that we're able to avoid those normal tissues better, but still treat the areas that we want to treat.

Stereotactic body radiation therapy, or SBRT, is probably the newest kid on the block in our toolkit. And ultimately that uses very, very high precision in the way that we're planning to really just target individual tumors. So when I described what intensity modulated radiation was, we talked about treating a broader swath of tissue. This would be used in the setting of maybe one area, like one lymph node or one area along like the pelvic sidewall that needed a high dose of radiation, but ultimately we didn't need to treat anything else that was nearby. And so that can be a really, really helpful treatment. And it works a little bit more as what we call an ablation, which is a little bit different than how traditional radiation, or intensity modulated radiation works.

Gamma knife is a very specific type of stereotactic body radiation, was kind of the first that developed. And ultimately that's used to treat brain tumors. And so that uses a very specialized machine that really just targets brain tumors specifically. But it's kind of a variation of stereotactic body radiation.

Scott Steele: And one other question that gets brought up a lot is proton therapy. Is that radiation oncology, and how is that different? And is that used in colon and rectal cancer?

Sudha Amarnath: Sure. Proton therapy is basically what we call particle therapy and it is administered by radiation oncologists. So more traditional kind of radiation uses what we call photons, which are very, very high energy x-rays. Protons are a particle and they have different physical characteristics than photons do. And so, not getting too technical with the physics, but basically protons can be really helpful in areas where there is really critical normal structure that's nearby.

So let's say for example, there's a tumor that's in the spine. And it needs to be treated to a high dose of radiation, and we're concerned about the spinal cord getting too much radiation. So protons can be used in that setting to really target that tumor in the spine, but prevent radiation from really getting to the spinal cord. And so there are really specific instances where protons can be helpful. Like I mentioned in the spine, in the brain, kind of near the brainstem. We think about it a lot in pediatric patients because we want to minimize kind of the overall radiation exposure to our younger patients.

In the setting of colorectal cancers, there's much less data that protons are really beneficial, because again, we're trying to usually treat a broader swath of tissue to prevent the cancer from coming back in the pelvis as a whole. And so protons tend to be a little bit more helpful in really localized treatment, but there's less evidence that it's as helpful when we need to treat a broader area.

Scott Steele: So let's go into a segment I like to call Truth or Myth. So Truth or Myth: a patient is unable to move at all when receiving radiation therapy for colorectal cancer.

Sudha Amarnath: So that's a little bit, I'll call that a partial truth. So typically, we want our radiation to be delivered really precisely and accurately, and so we don't want people to move around too much during their treatment. But that being said, we are able to start and stop the radiation treatments. And so if someone has a little tickle or needs to cough, we can always pause their treatments.

And so it's not like they have to be totally still the whole time, because I know people get anxious about that. There are always cameras and microphones in all of the treatment rooms. And so ultimately, if someone has to move for some reason during that treatment time, they can definitely do so.

Scott Steele: Truth or Myth: patients who have issues with claustrophobia will have trouble, or even cannot undergo radiation therapy.

Sudha Amarnath: So I would say that one is a myth. Ultimately, our machines are in very large rooms. So a lot of times people worry that the linear accelerator, which is the radiation treatment machine, is going to be kind of like an MRI, which is a much more enclosed machine that the diagnostic radiologists used to get pictures. The radiation therapy rooms are nothing like that. They are very large, wide open and most patients do not experience any sort of claustrophobia as they're going through treatment.

Occasionally when we have to treat cancers that are in the head and neck area, we use a mask to essentially help immobilize their head and prevent their head from moving during treatment. And occasionally some people will get a little bit of claustrophobia when we have to use a mask like that, but we have several techniques that we can use to help them through that process. And usually after the first couple of treatments, it becomes old hat to the patients. And a lot of times that feeling of anxiety and claustrophobia tends to really diminish and go away as they continue through treatment.

Scott Steele: So I'd encourage all of our listeners to go back to the 2019 episode we had with Dr. Amarnath to talk a little bit more about the side effects, we won't go into those in this episode. But as we wind up here, what's on the horizon as far as the future of using radiation therapy to treat colorectal cancer?

Sudha Amarnath: As Dr. Steele knows, this is a really exciting time in the world of colorectal cancers, especially rectal cancers, because there's a lot of innovation that's happening in the way that we think about taking care of patients. And so radiation is now being used a little bit more as a primary therapy to get rid of cancers in select patients, and ultimately omitting the need, occasionally, for surgeries in some of these patients.

We're using more techniques like stereotactic body radiation therapy, or SBRT to treat tumors that might come back in the pelvis or sometimes tumors that have spread to other parts of the body, like in the liver or the lungs. So I think there's a lot of really exciting things that are happening right now in the world of radiation for patients with colorectal cancers.

Scott Steele: And as you know we like to wind up with all of our experts, a little bit of our quick hitters. I've asked you some in the past so let's ask you a couple of different questions to get to know you a little bit better. So what's your favorite movie?

Sudha Amarnath: Ooh, that's a tough question. One of my favorites growing up that my sister and I always loved to watch was The Fugitive. So I'll say that, but it's a tough one. I love movies.

Scott Steele: That's a good one. So what's your favorite song or artist?

Sudha Amarnath: Good question. I like to listen to a pretty wide variety of music, but one of my favorites, and probably the band that I've seen the most often in concert, is U2, or The National.

Scott Steele: Although I asked you this in the past, I'll ask you it one more time. What's the last nonmedical book that you've read?

Sudha Amarnath: I was on maternity leave this summer so I actually had a lot of time to read. The last book I read actually was a book called Olive Kitteridge, which was a great book of short stories with a central character. So that was really enjoyable.

Scott Steele: And although most of us got a little bit nauseated when you mentioned your love for Michigan, what is one thing you like about the Northeast Ohio area over Michigan, as we wind up our last quick hitter?

Sudha Amarnath: Ooh, well, living in Northeast Ohio compared to where I grew up in Lansing, much closer to the beautiful Great Lakes. And so I do love living so close to Lake Erie and being able to just go to the lake whenever I want. So that part is really lovely.

Scott Steele: Give us a final take home message for our listeners regarding radiation oncology here at the Cleveland Clinic for patients who are treating colorectal cancer.

Sudha Amarnath: I think our goal in radiation oncology is to make patients as comfortable as possible, and to really treat everyone as an individual and personalize and tailor their care in the best way possible. So ultimately, we really work as a team here with our surgeons, with our medical oncologists. And again, we just really want patients to have the best experience possible and to know that we treat everyone as an individual.

Scott Steele: That's fantastic stuff. And to learn more about colorectal cancer, and specifically radiation therapy treatment options, please visit clevelandclinic.org/cancer. That's clevelandclinic.org/cancer. C-A-N-C-E-R. And to make an appointment with Cleveland Clinic's Cancer Center, please call our cancer answer line at 866.223.8100. That's 866.223.8100.

And just remember, in times like these it's important for you and your family to continue to receive medical care. And be rest assured that here the Cleveland Clinic, we're taking all the necessary precautions to sterilize our facilities and protect our patients. Dr. Amarnath, thank you so much for once again joining us on Butts & Guts.

Sudha Amarnath: Thanks so much, Scott.

Scott Steele: That wraps things up here at Cleveland Clinic. Until next time, thanks for listening to Butts & Guts.

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Butts & Guts

A Cleveland Clinic podcast exploring your digestive and surgical health from end to end. You’ll learn how to have the best digestive health possible from your gall bladder to your liver and more from our host, Colorectal Surgery Chairman Scott Steele, MD.
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