Chris Beltran, Ph.D., found his calling looking at the bright canvas above him. There, high above the Sangre de Cristo Mountains in rural northern New Mexico, lay constellations of stars and planets like Mercury, Venus, Mars and Jupiter.
As a student, Dr. Beltran kept focused on the skies, receiving a scholarship to study the ways Mercury disobeys Newtonian mechanics. He traveled northeast to Indiana University in Bloomington for his doctorate, intending to do experimental work on string theory.
“But there aren’t that many jobs in string theory,” he said with a laugh. So, he switched to another interest with more real-world application — nuclear physics.
At Indiana, he studied proton spallation, shooting protons at different atoms and studying what those atoms ejected in the collision. This is when he first learned about ion therapy, the cutting-edge therapy that can attack difficult-to-treat cancers that resist radiation and chemotherapy. He would come back to ion therapy and use it at Mayo Clinic, but first he returned to New Mexico to finish his doctorate at Los Alamos National Labs, which led to a residency at Mayo in 2004.
By then, work had already started on using proton therapy for cancers, and Dr. Beltran has taken the lead on improving and extending the technique.
Now as a faculty member and medical physicist at Mayo Clinic in Florida, Dr. Beltran is not only pioneering ion beam therapies, but also working to improve accessibility for the many patients for whom these techniques are often unavailable.
Beyond the math and physics, he is working to make patients’ lives easier and calmer throughout the treatment process.
“I want to understand what the patient goes through,” he said. “Anything you can do to actually make the treatment quality better but also decrease the amount of time patients have to spend there on the table, we should do.”
"I want to understand what the patient goes through."
That’s why Dr. Beltran has simulated the patient experience by going to the treatment table and lying motionless for the treatment’s half-hour timetable. He wants to improve future therapies in an effort to provide the best possible patient experience.
Improving the Options
Traditional radiotherapy has been successful for a variety of cancers, but it has its drawbacks. Radiation works by wreaking havoc on a tumor cell’s DNA until the damage becomes irreparable.
But it’s difficult to focus on just the tumor — radiation can damage a patient’s normal tissue, creating single-strand breaks in cellular DNA that may or may not get repaired.
This can result in side effects, like memory loss and fatigue. On top of that, many cancer types can repair radiation-induced damage and won’t even respond to this kind of treatment.
Some cancers, like bone sarcomas in the pelvis, can grow so rapidly and with such tenacity that the dose of radiation needed to combat it would just harm the patient more. Hypoxic and recurring tumors are also frequently beyond the reach of radiation or chemotherapy.
Proton therapy is a promising alternative that uses a synchrotron, a particle accelerator, to whip protons into a swiftly moving stream that can more directly damage tumors with fewer side effects. And Mayo Clinic, with Dr. Beltran as part of a dynamic leadership team, is bringing a new improvement over proton therapy: carbon ion therapy.
All these treatments have the same general scientific concept — hurl high-energy particles at cancer cells to destroy their genomes — but carbon ion therapy comes with a quantum leap of precision. A carbon ion is 12 times heavier than a proton and delivers magnitudes more energy in tighter clusters.
“This creates a bunch of breaks in small areas, like little explosions,” says Dr. Beltran. “You create so many breaks that the cell can’t repair them all and it dies.”
Radiotherapies also stimulate tumors to release antigens into the bloodstream, with carbon ion therapy producing more antigens than previous methods.
That means, Dr. Beltran says, that it could be nicely combined with something like chimeric antigen receptor T-cell therapy — known as CAR-T — where immune cells are programmed to detect specific antigens and attack tumors.
Thinking of Patients
Through all his experience, Dr. Beltran has learned a critical bit of wisdom when building medical treatments: think of the patient perspective.
“The technical aspects of this fall on me and my team. When we turn on the beam, we have to get the best-quality treatment to the patient,” says Dr. Beltran. “Patients are coming in every day for several weeks, and we need to provide the best experience possible for them.”
Dr. Beltran views his position — a physicist surrounded by doctors, nurses and patients — as a critical fulcrum for many patient outcomes.
“It’s our responsibility to understand all the fundamental physics and to communicate it to the medical staff, the doctors and nurses, so they can communicate it to the patients,” he says. “With carbon ion therapy it’s not just the physics — there’s the biological aspect.
“Normal tissues and tumors react differently, so when something does come up, you can have an informed opinion on different cases.”
Mayo Clinic is investing more than $233 million in a transformational proton and carbon ion center known as the Integrated Oncology Building at its Florida campus, and Dr. Beltran is involved every step of the way.
Millions of electrical connections are being made just for the synchrotron alone, with shielding 3- to 5-feet thick. The synchrotron itself has a 60-meter circumference, is made up of hundreds of tons of auxiliary equipment, and can hit a tumor with precision within 1 millimeter. The facility is the size of a football field. Dr. Beltran wants to be there when it’s all put in place.
“I go once a week to look at the building and see how it’s coming up,” he says.
Besides checking in on the new center, he frequently visits Japan — where carbon ion therapy is already in use — to meet with collaborators and inspect equipment that the electronics manufacturer Hitachi is producing for the center. Hitachi had never built the kind of facility that Dr. Beltran is working on — one that can deliver both proton and carbon ion therapies simultaneously.
However, just bringing new technologies and new treatment options to the United States isn’t enough. Mayo’s ion therapy center in Florida will be the first and only of its kind in the Western Hemisphere.
"It’s very important for the U.S. to be at the forefront of clinical therapies and patient experiences. I’m glad Mayo Clinic is leading the way."
Dr. Beltran estimates that between 30,000 and 200,000 patients per year in the United States could benefit from carbon ion therapy alone. The new facility initially will be able to handle 300 carbon ion patients per year. That leads Dr. Beltran to his true North Star for the patient experience — making these therapies even more accessible to all.
“It’s very important for the U.S. to be at the forefront of clinical therapies and patient experiences,” Dr. Beltran says. “I’m glad Mayo Clinic is leading the way.”
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