The Peter Attia Drive
#343 – The evolving role of radiation: advancements in cancer treatment, emerging low-dose treatments for arthritis, tendonitis, and injuries, and addressing misconceptions | Sanjay Mehta, M.D.
Mon, 07 Apr 2025
View the Show Notes Page for This Episode Become a Member to Receive Exclusive Content Sign Up to Receive Peter’s Weekly Newsletter Sanjay Mehta is a radiation oncologist with over 25 years of experience, and is currently the president of Century Cancer Centers in Houston, Texas (drsanjaymehta.com). In this episode, Sanjay explores the rapidly evolving field of radiation oncology, addressing common misconceptions about radiation exposure. He delves into radiation’s critical role in modern oncology, examining recent advancements that precisely target tumors while minimizing damage to surrounding healthy tissues and reducing side effects, with specific insights into breast, prostate, and brain cancers. Sanjay discusses fascinating international practices involving low-dose radiation therapy for inflammatory conditions such as arthritis, tendonitis, and sports injuries, highlighting its effectiveness and potential for wider adoption in the United States. Wrapping up on a lighter note, Peter and Sanjay discuss their mutual passion for cars and reveal how this shared interest first brought them together. We discuss: How radiation oncology became a distinct, rapidly evolving medical specialty [2:45]; Defining radiation, ionizing vs. non-ionizing, and common misconceptions about radiation exposure [5:30]; How radiation doses are measured, real-world examples of radiation exposure, and safety practices [9:00]; Radiation doses from common medical imaging tests, and why benefits of routine imaging outweigh risks [14:15]; Therapeutic radiation oncology: the evolution of breast cancer treatment toward less invasive surgery combined with targeted radiation [23:30]; Modern radiation oncology treatments for breast cancer—minimizing risks and maximizing patient comfort and outcomes [27:15]; How advances in radiation dosing, technology, and treatment precision have significantly reduced side effects [39:45]; How breast implants affect radiation treatment [44:45]; Radiation therapy for prostate cancer: advancements in precision, effectiveness, and patient selection criteria [48:00]; Radiation therapy options for inoperable prostate cancer or those seeking alternatives to surgery, and a remarkable patient case study [55:15]; How patients can effectively evaluate and select a high-quality radiation oncologist [1:05:45]; Radiation therapy for brain cancer: the shift toward precise, targeted techniques that minimize cognitive side effects, and remaining challenges [1:08:30]; The origins of radiophobia and how it influenced perceptions of radiation use in medicine [1:18:00]; Treating chronic inflammatory conditions such as tendinitis, arthritis, and more with very low-dose radiation [1:23:45]; Using low-dose radiation to treat spine injuries, scar tissue, fibrosis, keloids, and more [1:30:00]; The current barriers preventing widespread adoption of low-dose radiation therapy for inflammatory conditions [1:35:45]; The durability and versatility of low-dose radiation therapy in treating chronic inflammatory and arthritic conditions [1:40:45]; Sanjay’s talent as a drummer [1:44:45]; Peter and Sanjay’s shared passion for cars and racing [1:47:15]; and More. Connect With Peter on Twitter, Instagram, Facebook and YouTube
Chapter 1: What advancements are being made in radiation oncology?
If you want to take your knowledge of this space to the next level, it's our goal to ensure members get back much more than the price of a subscription. If you want to learn more about the benefits of our premium membership, head over to peteratiamd.com forward slash subscribe. My guest this week is Dr. Sanjay Mehta. Sanjay is a radiation oncologist at St.
Joseph's Medical Center in Houston, Texas, where he's been in practice for more than 20 years. I wanted to have Sanjay on the podcast to talk about all things pertaining to radiation oncology, but also the history and some of the misconceptions around radiation exposure and radiophobia.
We talk about some of the very interesting applications that I only learned about recently that are very common outside of the United States that involve low-dose radiation to treat inflammatory conditions and athletic injuries. Now, of course, those of you who are interested may recall that because this podcast is called The Drive, I do occasionally talk about cars.
Chapter 2: What are the misconceptions about radiation exposure?
And given that Sanjay and I have a shared passion for them, and in fact, that's how Sanjay and I met, we do end this discussion with a little bit of a deep dive into CARS. But of course, back to the main point of this discussion, we talk about the evolution of breast cancer, including the shift from radical mastectomies to more conservative approaches like lumpectomies and sentinel node biopsies.
We talk more broadly about the role that radiation plays in modern oncology, how doses have changed, and how advancements in targeting tumors while minimizing damage to surrounding tissues have rendered side effects much more rare, certainly more rare than they were even 20 to 25 years ago.
Sanjay talks about the role of low-dose radiation for inflammatory conditions such as arthritis and tendonitis, and how this approach is more widely used outside of the US, and why it's his hope and mine that becomes more adopted here in the US. We speak about the history and misconceptions of radiation exposure, including radiophobia, nuclear accidents, and early uses of radiation.
So without further delay, please enjoy my conversation with Dr. Sanjay Mehta. Sanjay, welcome back to Austin. Thank you, Peter. Pleasure to be here. I think this is the first time we're together not driving, right? I think so. Yeah, that is true. I don't know. Somehow we're going to resist the urge for most of this discussion to not talk about cars. Don't want to bore your audience. I know.
It is called The Drive.
This is true.
So I feel like we will reserve the right to have some automotive discussions at the end. For listeners, Sanjay might be one of the most knowledgeable human beings on cars. He's also a very dangerous friend to have. Because he's always the bad one on the shoulder when you're contemplating a new set of wheels or a new something for your cars.
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Chapter 3: How is low-dose radiation used for treating injuries?
But in his other life, in addition to being the founder of MD Motorheads, right? That's right.
Yeah.
which is a Facebook group of doctors who are gearheads. We're about to crack 3,000 members. It's exploded. Yeah. That's awesome. So shout out to MD Motorheads. You're also a radiation oncologist, which we also spend some time talking about. Right. I guess we thought it would be a really fun idea to do a podcast for a couple of reasons.
One is just the bread and butter of what you do as a radiation oncologist is a bit of a black box to many people, myself included, if I'm going to be completely truthful. Even training in surgical oncology, I feel like I had much more familiarity with the medical side of oncology than I did with the radiation side of oncology.
So for myself, for the audience, I think it would be wonderful to understand more about as it's a field that has evolved a lot. I'm guessing the last 25 years has seen a lot of change.
It's one of the youngest fields, too, in that respect. It's not steeped in some of the traditions that surgery and medicine are. So, yeah, it's a new field, highly evolving very rapidly, and the technology has changed so much just in, really, in the last decade or two.
It's pretty incredible. Just out of curiosity, when did it become its own discipline, its own set of boards and everything like that?
As a kid and growing up in Houston, some of my family friends were radiologists. And I remember just like probably an elementary school kid that some of them were talking about radiotherapy. And these were diagnostic radiologists who at the time, CT scanning was pretty new in the 80s. Prior to that in the 70s and then prior to that, it was kind of just a fellowship.
Radiologists would have a Cobalt 60 machine that they would train on for a few weeks and you do a few easy calculations and do some crude treatments. But it really started, it came into its own starting in the 70s and really more into the 80s. And that's when it became its own discipline. The ACR had a separate carve out. And so our residency training is completely independent of diagnostics now.
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Chapter 4: What role does radiation play in breast cancer treatment?
I think a lot of people are going to be very interested in this idea that why aren't we using low-dose radiation more to heal some of these nagging orthopedic injuries that people have? And of course, we'll go far down the rabbit hole on that. But I don't think we can have this discussion without giving people some understanding of what radiation is.
And I would like us to do it in a way that's both rigorous enough that we can really get into some of the science of this, but also get into it gently enough that people that maybe don't remember high school physics well enough can come along for the ride and not get lost.
But once we get into grays and millisieverts and all that stuff, I want everyone to be fluent when we start talking about doses. Right, right, right.
radiation itself, the term itself has got a bit of a negative connotation, but basically it's part of the electromagnetic spectrum. So we have everything on the one in the range of increasing energy of photons, which are just particles of light. On the one end, you have radio waves and microwaves. On the other end, you've got infrared and, excuse me, you've got
ultraviolet and then you get into x-rays and radio waves. And in the middle of all that is the visible spectrum. So when you see, I'm sure everyone's seen the graphs where you've got the rainbow, red, green, blue that we can see, the human eye can only perceive a tiny little narrow spectrum. These are wavelengths.
These are actually wavelengths and energies which are the very low-end energies you have things like radio waves. In that situation, both radio waves and microwaves are what they call non-ionizing. And I know you've talked about this on some of your previous podcasts. I know you had a really good one with Atariwala from Prenuvo. It was a really nice in-depth discussion.
But essentially, the bottom line is that the low-energy stuff that is non-ionizing cannot damage tissue. And that goes all the way up to visible light. Then when you start going to the higher-energy X-rays, that's when you get both X-rays as well as ultraviolet light and then the higher-particle stuff. But basically, the higher you go in the energetics of the particles, the more likely...
exposure to these packets of energy are going to cause damage to your DNA.
Why is it that the shorter the wavelength, because that's what's changing as you go from radio waves to microwaves to visible waves to ultraviolet, why is it that as the wavelength gets shorter, the energy gets bigger?
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Chapter 5: How has radiation therapy evolved for prostate cancer?
Chapter 6: What are the effects of radiation on patients with implants?
Correct. Correct. So when you give 70 gray, you're giving 70 sieverts or 70,000 millisieverts over the course of the treatment? That's correct. Okay. Just so people can kind of anchor this to things that are familiar. Living at sea level exposes us to one to two millisieverts of ionizing radiation a year.
That's exactly right. At altitude, it could be double that. That's right.
If you live in Denver, it's easily double that or triple that, correct? Just another thing for comparison, a pilot who spends a lot of time traversing The North Pole, which is typically how they're going to fly, they're not going to go all the way around the center of the Earth, might get another three or four millisieverts of radiation.
It's quite a bit. Quite a bit. That's right. Per trip, actually. So that can add up. And I was actually talking to a pilot friend about this. They don't really have any limitation in terms of total exposure that requires them to be taken out of the air. A lot of them, they're forced to retire at 65, I think is the commercial requirement.
But they don't really monitor the actual exposure to that level twice. I think the reason they don't really use that as a limiting factor for the amount of work is really just that even though they get a higher dose, there's been no proven increase in cancer in those types of populations, even in flight attendants or anything like that.
The same way that people in Denver and the people here in Texas don't have any higher incidence of cancer.
Now, the NRC recommends that a person not be exposed to more than 50, I believe, 50 millisieverts of radiation in a year. Now, someone like me, that's easy unless I'm out there getting a lot of diagnostic radiology or, of course, undergoing therapeutic radiation treatment. But for someone like you who has to set patients up or one of your techs Are you guys approaching that level of exposure?
Not at all. And so it depends on what type of radiation we do. Now, typically for our external beam machines, we're doing it all remotely from behind a shielded wall. So the vault in which the machine is placed is custom built just to shield based on the angles that the machine can move through.
If there's like a direct angle where the machine is hitting a wall, that wall has to be built 10 times thicker than the walls where the beam can't reach. So essentially our dose... when treating remotely is close to zero.
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Chapter 7: How can patients choose a high-quality radiation oncologist?
That might get you up another 10%. So let's talk about a chest X-ray. You got a cough, you go to your doctor, they do a chest X-ray. That's how many millisieverts for a normal size person?
Normal size person, it's a fraction. It's probably less than one millisievert actually. So it's significantly, it's something that where people who are concerned about things like diagnostic mammograms and all every year, you're still talking about maybe one millisievert or even a little bit less than that with some of the newer machines.
You're in a zone where there's a principle we talk about, it's called ALARA, A-L-A-R-A, which is as low as reasonably achievable. And that's been the mantra for our radiation safety people, the Nuclear Regulatory Commission and whatnot, that you want to keep things as low as possible. But having said that, when you're talking about numbers of less than 50 millisieverts,
That's kind of an arbitrary number. I should have maybe gotten a test actually when I had my cough last time, but I just don't want to do it. I don't want the exposure. But it's so minimal in terms of biologic effect that we really don't even really worry about those, even if it's getting one of them a month or so.
And a big reason for that is a lot of these numbers, especially the 50 millisievert number, is extrapolated from higher exposure rates. There's something called a linear no-threshold model, or LNT, and that's been written about extensively, and that's what we're all taught in radiobiology and residency.
One-fourth of my radiation training in residency was actually radiation biology, in addition to clinical oncology and radiation physics. So the linear no-threshold model is what states that we know based on all the data from nuclear fallout from Chernobyl, from Three Mile Island, of course, from Hiroshima and Nagasaki, from the bombs, that
At a certain dose exposure, there's a certain risk of developing a cancer or any other endpoint, whether it be dermatitis or bone marrow suppression. These numbers are well sorted. But when you try to extrapolate lower, so you take maybe, say, a dose of one full sievert, the 1,000 millisievert, and you start extrapolating that lower and lower to where you're looking at 100 or 50 millisieverts,
The linear model assumes that there's some level of damage even at those lower levels. But in reality, there's actually a threshold. The LNT, which is linear no threshold, has actually been proven to be actually erroneous. And so at very low doses, it's actually been shown that there's almost no incidence of any sort of biological damage.
And there's also, it's controversial, but there's animal studies showing there may be a hormesis effect at low, low doses like that.
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Chapter 8: What challenges remain in brain cancer radiation therapy?
Yeah. For folks who want to know more about that, Sid Mukherjee, I think it was in The Emperor of All Maladies, has a chapter on this.
Fantastic book and one of your best podcasts. Love that guy. Yeah, he's a legend.
So let's talk about that. So a woman has a stage one or a stage two breast cancer. Typically these days, I think they're moving mostly to neoadjuvant chemo before resection.
Yes, in a more advanced case. But if it's a typical T1 or even a small T2 that we see, they may not need any neoadjuvant therapy. They just will If it's, like I say, a one and a half centimeter mass that's easily resectable, they'll remove that just without any neoadjuvant treatment.
And we'll do adjuvant radiation and then potentially, depending on the receptor status, adjuvant hormone therapy, which is the domain of the medical oncologist, but we still work with them. So just surgery followed by three to four weeks of radiation. How long after surgery can you begin radiation? Wound healing, we give them a little bit of time.
We generally do our CT-based simulation and three-dimensional planning maybe two to three weeks after their surgery. And then by the time, it takes about a week to do all of our computer programming, and then we'll start the treatment within three to four weeks post-op.
So tell me a little bit about that. I was completely unaware of that. So I'm a woman, I've had a lumpectomy, sentinel node was negative. So I've got an incision about this long for the listener, five centimeter, six centimeter incision. They've probably closed it with beautiful internal sutures. I've got some steri strips. They're off in a week and I've got a nice little scar a week later.
I come and see you how many weeks after that?
I usually will see patients for consultation. A lot of times the breast surgeon will send them prior to anything being done. So I'll see them for their initial consultation ahead of time.
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