Making Cancer Care Globally Accessible With Stephen Towe
Episode Summary
In this episode of The Cancer Project Podcast, host David Raubach sits down with Stephen Towe, CEO and co-founder of Leo Cancer Care, to explore one of the most ambitious missions in modern oncology: making proton therapy globally accessible. Towe, a physicist by training who entered medical physics after losing his father to cancer, traces his path from designing hardware at Elekta — including work on the MR-guided Linac — to leading a startup that is fundamentally reimagining how radiation is delivered to patients. His personal motivation is never far from the surface, and it shapes every strategic decision Leo Cancer Care has made since its founding.
The central innovation behind Leo Cancer Care is deceptively simple in concept but radical in practice: rather than rotating a massive gantry around a stationary patient, Leo’s system keeps the radiation beam fixed and moves the patient instead. This inversion of conventional design philosophy, developed initially by a research group at the University of Sydney led by former Stanford professor Paul Keall, strips away roughly 75% of the cost and mechanical complexity that has historically made proton therapy a technology limited to large academic medical centers. A conventional proton gantry stands 36 feet wide, weighs 100 tons, and must rotate with millimeter precision — a feat of engineering that demands enormous concrete vaults and equally enormous capital budgets. Leo’s approach collapses that footprint to something that can fit inside a standard linear accelerator vault, a goal that clinicians in the field once described as impossible.
Towe describes an unconventional journey from London to Sydney, and then from Sydney to San Francisco, each move driven by the need to find the right capital environment to bring the technology to market. When the original Australian entity ran out of funding and went bankrupt, Towe — who had no background in venture fundraising — Googled the top medical device investors, identified San Francisco as the hub, and relocated. After securing initial investment and determining that Madison, Wisconsin offered dramatically lower operating costs and an established supply chain from companies like Accuray, Leo set up operations there. Rock Mackey, an industry legend known for co-developing TomoTherapy and the Pinnacle treatment planning system, joined early as an adviser and board member, lending credibility to a company that most of the field still viewed skeptically.
The clinical case for treating patients in the upright position — sitting in a chair rather than lying on a table — emerged as a secondary but powerful benefit. Research from MD Anderson and Mark Pankuch at the Northwestern Proton Center had documented measurable reductions in organ motion when patients are upright, improving dose conformality. Sophie Towe, Stephen’s wife and Leo’s marketing director, gave this clinical reality a compelling human framing: people facing the most frightening moment of their lives instinctively want to be upright, engaged, and empowered — not lying flat on a table in a machine. Her campaign around “a more human way to deliver radiation therapy” drew on her background leading campaigns for McDonald’s and Volkswagen rather than on healthcare industry conventions, deliberately avoiding the homogenized messaging that tends to circulate when marketing directors move between radiation therapy equipment companies.
By 2025, Leo Cancer Care had accumulated 39 commercial contracts spanning proton therapy, carbon ion, FLASH electron radiotherapy, and conventional photon radiotherapy — a far cry from the 2018 Estro conference in Barcelona where Towe could not get a single customer meeting. The most significant recent milestone is FDA clearance for the Leo-Mevion FIT system, a partnership in which Mevion supplies the world’s smallest proton accelerator and Leo provides the rotating patient positioning system and integrated CT imaging. The FIT name reflects the system’s defining achievement: the entire proton therapy setup fits inside a linear accelerator vault. With installation complete at Stanford and state licensing underway, the first patient treatments are expected in 2025 — closing a journey that began in a Sydney office the size of a single room.
What You’ll Learn in This Episode
- Upright Patient Positioning: Leo Cancer Care treats patients seated upright rather than lying on a table, keeping the radiation beam fixed while the patient moves — eliminating approximately 75% of the mechanical complexity and cost of a conventional gantry system.
- Proton Therapy Access Gap: Despite being considered the gold standard for treating many cancers, proton therapy has historically been inaccessible to most patients worldwide due to the enormous size, weight, and cost of conventional rotating gantries, which can weigh 100 tons and stand 36 feet wide.
- The FIT System: Leo’s partnership with Mevion produced the FIT system — the first proton therapy setup designed to fit inside a standard linear accelerator vault, opening proton treatment as an option for the thousands of existing Linac facilities that lack space or capital for conventional proton construction.
- FDA Clearance: The Mevion-Leo FIT system received FDA clearance in 2025, transitioning the technology from factory prototype to a device legally ready for patient treatment — a milestone Towe describes as a critical inflection point for commercial momentum.
- MR-Guided Linac Background: Before founding Leo, Towe was product owner at Elekta for the MR-guided Linac project — a system that combines MRI imaging with radiotherapy delivery, requiring engineers to solve the fundamental incompatibility between strong magnetic fields and radiation beam delivery.
- University of Sydney Origins: The rotating-patient concept originated with a research group at the University of Sydney led by Paul Keall, a former Stanford professor, who was initially trying to address cancer access disparities in rural Australia, where patients living outside Sydney and Melbourne are 30% more likely to die from cancer.
- Early Clinical Champions: Vincent Gregoire at the Centre Leon Berard in Lyon, France, and Mark Pankuch at the Northwestern Proton Center provided early external validation — Gregoire for his interest in bringing protons into a European urban center, Pankuch for his hands-on experience treating patients upright and his specific feedback on the practical challenges to solve.
- University of Wisconsin Contract: The first commercial contract in the U.S. came from the University of Wisconsin, where department chair Paul Harari had spent eight years trying to get proton therapy approved internally — a goal that always made clinical sense but never made financial sense until Leo’s lower-cost model changed the equation.
- Human-Centered Marketing: Leo’s marketing strategy, led by Sophie Towe, was built by deliberately hiring outside the radiation therapy industry — drawing on experience from consumer brands — to create messaging around treating patients as human beings rather than as cases, centered on the concept of empowerment through upright positioning.
- The Leo Name: Leo is the constellation that follows Cancer in the zodiac, chosen to reflect the company’s mission of always coming after cancer. The name also carries associations with lions, symbols of strength in many Asian cultures — aligning with Leo’s goal of expanding access in global markets.
- Organ Motion Reduction: Clinical research published by teams at MD Anderson and Northwestern demonstrated that treating patients in the upright position reduces internal organ motion compared to the supine position, which can improve the precision of dose delivery to the tumor and reduce exposure to surrounding healthy tissue.
- 39 Commercial Contracts: By 2025, Leo Cancer Care had signed 39 commercial contracts with end users across proton therapy, carbon ion therapy, FLASH electron radiotherapy, and conventional photon radiotherapy — reflecting the broad applicability of upright patient positioning across radiation modalities.
Stephen Towe’s story is a reminder that the most consequential advances in cancer care often begin not in a boardroom or a well-funded lab, but in a small office, driven by grief, physics, and the refusal to accept that a better approach is impossible. From his father’s cancer diagnosis to an FDA-cleared system now installed at Stanford, Towe has built Leo Cancer Care around a single conviction: that every patient, regardless of geography or the size of their local hospital, deserves access to the best available treatment. For anyone working in oncology, investing in healthcare technology, or simply living with the reality that cancer touches nearly every family, this conversation is essential listening.
Full Transcript
Read Full Transcript
David Raubach: Well, Stephen, thank you so much for joining us today on the Cancer Project Podcast. I’m really excited to talk to you about all the great things that are happening with Leo, but also I want people to get to know you and your background as well because I think it’s a really interesting story. So, thank you for joining us.
Stephen Towe: No, really appreciate it. Thank you for having me.
David Raubach: So tell us a little bit about your training and how you ended up in the world of proton therapy.
Stephen Towe: Yeah, so I’m a physicist by background. Got into physics really just for a love of figuring out how things work. One of those annoying kids at school that’s always just, oh, why is it like that? So I’ve always loved physics and while I was studying physics at university, unfortunately my dad died of cancer. So I saw him go through what was a very difficult journey and it was just an opportunity really getting into radiotherapy to use that love of physics. It’s a very physics-heavy industry, and a passion of making a difference to cancer patients’ lives. So getting into developing technology originally and then now running Leo Cancer Care.
David Raubach: So for those listeners that are not familiar with how you end up as a medical physicist, what’s the training like to become a medical physicist?
Stephen Towe: Yeah. So you go first into university and study physics — the baseline physics, which is where I learned about particle accelerators and quantum physics as a particular passion. And then I trained in the UK rather than in the US. So then go and study specifically medical physics following that. It’s a broad range of applications of physics within the clinical setting. Radiotherapy, radiology — all of those areas of healthcare are heavy on the physics side.
David Raubach: What was your first job out of training?
Stephen Towe: So I went straight into Elekta. There was an opportunity to go into working in the clinic and that would have been great. But I think for industry, working in industry gives you that broader impact possibility. I can go and develop technology that is impacting millions of people. That always had a much stronger pull for me.
David Raubach: And so when you were with Elekta, what were you doing? Elekta makes linear accelerators, treatment planning software, the Mosaic medical record system. What in that broad spectrum were you doing?
Stephen Towe: Yeah. So I was really working within their physics team developing the hardware platforms. I’ve always been terrible with software — hate coding, which is a bit unusual for a physicist. So I was always on the hardware technology platform design. Things like designing calibration procedures specifically for the multileaf collimators, the bits that shape the radiation beam, all the way through to when I left Elekta being a product owner responsible for pretty much all of the physics activities on the MR-guided Linac. That was taking an MRI machine and putting it with a radiotherapy treatment platform to create this combined imaging and treatment modality.
David Raubach: The goal with radiation has always been how do you get as much radiation to the tumor as possible and as little radiation to healthy tissue as possible. So the MRI gives you a good view of what’s happening inside the body combined with the actual delivery of radiation — but those two things really don’t go together easily.
Stephen Towe: Exactly. MRI and radiotherapy are like putting oil and water together. The MRI will interfere with radiotherapy delivery and the radiotherapy delivery will interfere with the MRI imaging. So those two things really shouldn’t sit in the same room — which as a physicist makes it a really exciting project to work on.
David Raubach: So then you ended up leaving Elekta for different opportunities. Tell us about that transition.
Stephen Towe: Yeah. So I came out of Elekta and really got to the end of that project and while I was really excited and proud of what we’d developed, I couldn’t help but see it was bigger than conventional radiation therapy, certainly more expensive, and also more complicated — requiring more people in the treatment rooms and more training. That didn’t really fulfill the dream of how do we make radiotherapy available across the globe, which is something that’s always been important to me. So then I became aware of a research group down in Sydney in Australia, led by Paul Keall, who used to be a Stanford professor. They were looking at exactly that — how do we make radiotherapy globally accessible? How do we reduce the costs and get it to more people?
Stephen Towe: They came to the realization that the way of doing that is to keep the radiation beam fixed and to move the patient instead. Everybody else previously in radiotherapy development had the patient lay on a table and moved the radiation beam with respect to that patient. These guys were really bold in their thinking in saying, well, that movement of the radiation beam accounts for probably 75% of the cost. So if we change that and flip it on its head — if we instead move the patient — the costs and the complexity come down.
David Raubach: And you were in London at this time. So then did you move to Sydney?
Stephen Towe: I did. Never been down there before. Even if the job opportunity hadn’t been great, the idea of living in Sydney for a year and a half was pretty fantastic. So yeah, packed up my bags and moved to Sydney. I’d known my wife Sophie for about six months at the time. I remember taking her for dinner and saying, “Hey, Sophie — we’ve only known each other for six months, but I’m thinking about moving to Sydney.” And she went, “Oh, I’ve always wanted to go to Sydney. I’ll come with you.”
David Raubach: So you get there. Elekta is a big company with a lot of resources. This was a quintessential startup.
Stephen Towe: Yeah. The office was about the same size as the room that we’re in today with the entire team. No processes, no people, no big established office. It was a big difference. It was exciting, but it was also pretty terrifying — going from having people that did everything at Elekta to now having to figure out how to do all of that yourself.
David Raubach: When you guys were talking about doing upright treatments, was that just for photons or were there conversations about protons too?
Stephen Towe: Originally it wasn’t even in the upright orientation. The original idea was to have patients lay down and rotate them in the supine orientation. But it was all for photons. The reason that group started was because they were trying to address the lack of access to conventional radiotherapy in rural Australia. You’re 30% more likely to die from cancer if you live outside of Sydney and Melbourne — which in a country like Australia is pretty shocking. They were looking at putting these supine-rotating Linacs in trucks and taking them out to rural Australia. That’s where it started.
Stephen Towe: And then they realized the difference between academia and reality where you have real patients. The idea of supine rotation while great on paper didn’t actually make sense in reality. So that was the transition to upright. And once we got our heads around that, we found that people from MD Anderson had researched upright radiotherapy, Northwestern in Chicago had as well, and they’d proven out some pretty interesting clinical differences — organ motion reduction and things like that that happen when you’re upright rather than lying down.
David Raubach: There’s also the fundraising component and the “how do you get a product to market” element. You’re moving out of this medical physics world and starting to pick up on the business side. When did that start to become interesting to you?
Stephen Towe: It was certainly never my plan to become a CEO or go into the commercial side of things. I always wanted to stay in industry and design technology. But in Australia as we started to build out this idea, you’re exactly right — you need to raise money and find investors that believe in your vision. And in Australia that was a real challenge. Venture capital didn’t really invest in healthcare and medtech back then. So the company actually in its original form went bankrupt. It was not a grand design to go and learn how to raise money — it was more out of necessity.
Stephen Towe: With nobody else being in a position to leave Australia at that point, I said, “I’ve been spending years designing linear accelerators — how hard can it be to go and raise money for them?” So yeah. How wrong could I have been. I genuinely Googled “top 10 medical device investors” and saw San Francisco, San Francisco, San Francisco. So that was it. I knew I had to pack up my bags again and leave Sydney.
David Raubach: So you go back to Sophie. Are you guys dating or married at this time?
Stephen Towe: I was very strategic. I thought, okay, it’s not ideal that I’m going back to her again and asking her to move everything and relocate. So we got engaged before I asked her that time. She had agreed to marry me, so she was already committed. And then I went back and said, “Okay, to make this work, we need to leave Sydney and move to San Francisco.”
David Raubach: What were the early days like there in San Francisco? Somebody’s trying to raise money, you’ve never done this before.
Stephen Towe: That’s kind of what I was asking myself on a daily basis — what on earth am I doing here? It’s just going and meeting as many people as you possibly can. Networking like you’ve never networked before. Getting feedback, asking people why they’re saying no, and trying to understand how your pitch needs to change in order to start getting some of those yeses. Just meeting hundreds of people over the course of probably the first three months while I was there. Sending emails, going to networking events, literally walking into companies.
Stephen Towe: And when somebody’s really decided to invest, they’ve bought into your vision. It’s not only that they’ve decided to put money in that allows you to continue — it’s the feeling of knowing that somebody else buys into your vision. If you’re the only one out there pushing something, you kind of feel like, is this a good idea? Am I crazy? Once somebody looks at it and says, not only does that idea make sense, but you actually have a business that makes sense — that’s a great feeling. And then once we got the first one, it’s about getting momentum. Once you get one person buying in, you tend to be able to get multiple.
David Raubach: Rock Mackey is an industry legend — he changed the industry with TomoTherapy and the Pinnacle treatment planning system. How does he come into the story?
Stephen Towe: Rock was actually involved in Australia. When the research group was developed and decided to spin out as an entity, Rock was originally an adviser and then joined the first board of directors in Australia. And when we started getting some traction and the first investors came in, we realized it was just so expensive to build a business in San Francisco. If we built the business in Madison — which is where Rock lives, but also where companies like Accuray have been built, so there’s good supply chain and good talent — the cost of hiring people in Madison was 40 to 50% lower in some cases than San Francisco.
David Raubach: When did you really start to hone in on this being a proton therapy product?
Stephen Towe: As we engaged with industry experts they kept saying yes, it is a problem for conventional radiotherapy, but protons is a massive issue. There was no access or very limited access worldwide for a technology that is really the gold standard for treating cancer. And the reason for that lack of access was always size, cost, and complexity. So we realized that to solve the problem in Linacs could wait — we would first address this issue with proton therapy. Our gantry at a conventional facility is 36 feet wide and weighs 100 tons. You’ve got to shield it. You have this massive concrete bunker it sits in, and that whole thing has to rotate with millimeter or even micron precision around a patient. It’s the most complex medical device that’s ever been made.
David Raubach: Who were some of the early external champions outside the company who came alongside and said this really can work?
Stephen Towe: The very first research partner was Vincent Gregoire, based in Lyon in France. He had always wanted to put protons into that center and came across the same problems — gantries are really big, expensive, very difficult in a European city. When I first met him back in 2019 he just got it instantly. He’s one of these people where if you tell him something can’t be done, he doesn’t want to run away from that — he’s more likely to want to do it. And in the US, we got a lot of feedback from Mark Pankuch at the Northwestern Proton Center. He’d been treating patients upright for his thoracic tumors. He understood the benefits but was also able to say these are all the reasons I’ve struggled with it and these are the things you need to fix if you’re starting from square one. Then we got support from MD Anderson, and the first center that executed a commercial contract in the US was the University of Wisconsin — Paul Harari had tried for eight years to get proton therapy into his department. It always made clinical sense but the finances never worked. Until Leo changed the equation.
David Raubach: I want to talk about Nick Schroeder, someone I know well. He helped build a proton system in South Africa and then was at IU, building essentially an in-house system. He’s always had this attitude — if somebody says it’s impossible, Nick’s going to take it on. We built a chair in Oklahoma before Chicago, and it was very rudimentary, almost felt like it got built in a garage. But it worked. Then Chicago took it to the next level with Mark’s leadership. Talk about what Nick has brought to Leo.
Stephen Towe: Nick’s the most practical genius you’ve ever come across. I’ve met lots of really smart people that can come up with ideas, but the amazing thing about Nick is you come to him with a problem — say, I’m worried about quality assurance and how we’re going to do that — and not only is he going to say “don’t worry, here’s how we approach it,” but he’s also going to say “oh and by the way, I’ve built that solution in my shed. And I’ve found a supplier who can build it commercially as well.” He’ll never shy away from any challenge. He’s incredibly passionate about two things in life: proton therapy and barbecue. He raises his own meat and butchers his own meat — start to finish doing his own barbecue.
David Raubach: Where did the name Leo come from?
Stephen Towe: Leo is the constellation that comes after Cancer. As an organization, that’s our mission — we’re constantly coming after cancer, constantly trying to find ways of developing technology that will treat cancer patients. It’s also associated with lions, which particularly in places like Asia are associated with strength. Bringing those two things together, we got Leo Cancer Care.
David Raubach: You’ve done a great job with your marketing, and part of that was bringing Sophie on to help. Talk about what she’s brought to the company and the vision for how you’ve marketed Leo.
Stephen Towe: We made a very conscious decision that within our marketing team, we wouldn’t put anybody in there that was already in the industry. You tend to go around the other providers of radiation therapy equipment and it’s the same marketing directors going from company to company — and you can tell that the messaging all looks and feels very much the same. We didn’t do that. Industry knowledge can come from people like Rock and Nick — there’s nobody better to provide that. So Sophie had been leading campaigns at McDonald’s and Volkswagen, companies that are much more targeted with their marketing and frankly better at putting forward their messaging than a lot of healthcare organizations.
Stephen Towe: The whole idea of being “a more human way to deliver radiation therapy” was her baby. It came from this idea that human beings in the radiotherapy environment — whether protons or photons — that is without a shadow of a doubt the scariest moment in their life. And then we started thinking about other times people are scared: a big presentation, a job interview, meeting in-laws for the first time. In any of those situations, you wouldn’t choose to do it lying down. You’d always choose to be upright, engaged, and empowered. So by putting patients back at the center of their care in the upright position, we were doing exactly that — empowering them and giving them their humanity back at the time where they were really being referred to as just patients.
David Raubach: Now let’s transition to the product itself. You guys have had some big announcements recently. Talk about what’s happened over the last twelve months with Leo.
Stephen Towe: We really started from a point where everyone said it was crazy — a terrible idea that was never going to work, in 2018. I remember going to Estro in Barcelona and nobody wanted to meet. Everyone just thought it was a crazy idea. So to see it now go from 2018 crazy idea to 2025 where we’re in a position with 39 commercial contracts — with end users across not just protons but protons, carbon ion, FLASH electron radiotherapy, and now conventional photon radiotherapy as well — that’s an amazing journey.
David Raubach: Talk about your partnership with Mevion and the big announcement about FDA approval for the Mevion FIT system.
Stephen Towe: As a hardware company, to get an FDA clearance — that’s huge. That takes it from an idea and something built in the factory to something that is ready for treating patients. The way the partnership works: proton therapy relies on a few different things. You’ve got the bit that produces the radiation — the proton source. Then you’ve got to deliver that proton source to the patient, which is where we have our rotating patient positioning system and our integrated CT imaging. Mevion provides the accelerator — the smallest accelerator anywhere in the world for proton therapy. We provide the patient positioning and the imaging. And the combination gives us what we call the FIT product. The FIT name comes from the fact that the whole setup can fit inside of a linear accelerator vault.
David Raubach: That really has been the holy grail. Back when I was working at Procure in 2010 and 2011 we would half-jokingly say if you could ever figure out how to put protons in a Linac vault, that would create more access — because there are 4,000 plus linear accelerator vaults in the United States. And people said it was impossible.
Stephen Towe: Exactly. People said it was completely impossible, never happened to put protons inside a Linac vault. And Mevion has been a phenomenal partner in sharing that vision of let’s make protons accessible to all, not just big academic medical centers. So now we’re in a position where 200 people went to Stanford during this show to go and see that it’s real — this impossible task has been achieved with Leo Cancer Care and with Mevion. And they should be treating patients this year. Systems are FDA cleared, fully installed. They’ve got some state licensing to get pinned down, but they should be treating this year. It’s a long journey from a workshop in Sydney to Stanford treating the first patient on this system.
David Raubach: What are you personally most proud of?
Stephen Towe: I think most proud of the team that we’ve built and what they’ve been able to achieve. Our VP of engineering, for example — he never went to university, never got a degree in engineering. He went into industry as an apprentice, one of the smartest people I know. But he was always pigeonholed into a position where it was, “you can’t be responsible for developing anything because you haven’t been to university.” The fact that he’d spent years and years actually being hands-on and developing things didn’t matter. At Leo we brought him in and said — don’t show us the paperwork that proves you can do this; go and actually deliver. And to see him now leading our engineering team with tremendous engineers, we’ve created an organization that allows people to really fulfill their full potential. Seeing people grow like that, that’s something I’m incredibly proud of.
David Raubach: How have you taken the experience that you had with your dad going through cancer treatment to what you’re doing today? That must impact the way you approach your company.
Stephen Towe: It definitely does. My dad was a superhero to me. He was the best human being I’ve ever met. So being in a position where we’re developing technology that can make a difference to lives like his — we couldn’t do it for him, but to be in a position where we’re making a difference to other patients like him, that’s the driver. And when you’re building a company, it’s hard. It’s really, really hard. You get days where you don’t think it’s going to work. You get days where people say they don’t believe in it. You get days where people don’t want to fund it. If you’re motivated just financially, it just doesn’t work — you’ll bail when the difficulties come, and they come nine times out of ten with startup companies. For me, it’s always been about something so much more important than money. Throughout our organization you see people that have been directly impacted by cancer. For us to be able to go and take something like proton therapy that truly has the ability to save lives and take it to places it’s never been before — that’s a reason for getting out of bed in the morning.
David Raubach: Well, thank you so much for your time, Stephen. I really appreciate it. Congrats on all of your success personally and with the company. You guys are doing amazing things. As someone who’s been in the proton field for fifteen years now, I’m very excited to see this amazing technology create more access for patients to get proton therapy. And I know that you guys are also doing some great things on the Linac side, opening up rural and third-world markets to the power of radiation in treating cancer. I’m excited to see what’s ahead.
Stephen Towe: Wonderful. Thank you very much, David.
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