By: Kirsten Weir

Justin Bekelman, MD
Justin Bekelman, MD

Radiation therapy is an integral part of the treatment picture for many patients with breast cancer. But it sometimes comes at a cost: side effects including heart problems years later. Could proton therapy reduce some of those side effects while maintaining comparable cure rates to traditional radiation?

Penn Medicine is one of the world’s leading centers for proton therapy research. The Roberts Proton Therapy Center is also actively involved in clinical trials, including several national multisite trials currently underway, many of which focus on comparing protons to traditional X-ray radiation for different cancer types, such as esophageal or breast cancer. The ongoing Radiotherapy Comparative Effectiveness (RadComp) trial, for example, is the largest clinical trial to date to compare proton and photon therapy for patients with locally advanced breast cancer.  

“We did this study because we knew this was an important problem that patients cared deeply about,” said Justin Bekelman, MD, the Marietta and Howard Stoeckel Professor at Penn Medicine, who designed and leads the RadComp trial.

Patients involved in the study design and recruitment

Launched in 2016 with funding from the Patient-Centered Outcomes Research Institute, the RadComp study compares long-term heart outcomes and cancer control among 1,239 breast cancer patients randomly assigned to receive proton therapy or photon radiation therapy across the United States. In March 2024, the study reached the key milestone of completing patient enrollment.

From the start, the trial was designed to be “patient powered.” Bekelman and his colleagues worked closely with breast cancer patient advocates to design a study that would address patients’ concerns while making it easier for patients to participate in the research. The researchers also made sure patients were compensated appropriately for the time and effort they devoted to participating—an approach that is more common in 2024, Bekelman notes, but was novel when RadComp began in 2016.

Cynthia Chauhan, a retired social worker from Wichita, Kansas, who was treated for breast cancer at the Mayo Clinic in 2001, has been involved with RadComp since the beginning. She and other patient advocates meet regularly with the study leaders. They helped shape the trial’s key questions, trouble-shoot challenges and provide input on everything from communicating with participants to better engaging research participants from underserved communities. “This trial has involved patient voices from the very beginning, and we have been actively engaged throughout,” Chauhan said. “Whenever I’m speaking with someone about how to design a patient-centered trial, I tell them to call Justin Bekelman to find out how to do it right.” 

Following breast cancer patients long-term after radiation treatment

Bekelman and his colleagues will follow participants through 2031. Though it will be some time before final results are available, the team expects to publish analyses of patient-reported outcomes in early 2025 and cancer control several years after. 

Chauhan said she looks forward to the findings helping patients distinguish between two reliable treatment options to “guide us and our physicians in choosing the better approach to lengthen and improve our lives.”

Whatever the findings, Bekelman said, the trial is already a success. 

“RadComp is patient-centered and highly collaborative among enrolling institutions and physicians nationwide. And it will report on side effects and cancer control outcomes that are tremendously important to patients,” Bekelman said. “Those features make this study we designed at Penn an exemplary model for how to conduct randomized trials of advanced technologies, within cancer and beyond.”

Penn Medicine is driven to impact the world through breakthrough science, and RadComp is a prime example of that commitment, Bekelman added. Despite skepticism from many physicians and challenges from insurers, he and his colleagues were able to build on Penn Medicine’s reputation in the field to make the study a reality. “It takes a tremendous amount of courage and will to get a trial like this done,” he said, “and I’m very proud to say that in some ways it could have only been led by an institution like ours.”

The power of protons: related stories

The power of protons: Penn Medicine has treated more than 10,000 cancer patients with proton therapy—while leading the way in research on the healing potential of these positive particles.

Extending the reach of proton therapy: The world’s largest and most advanced center for proton beam radiation is applying its expertise to treat patients in communities beyond Philadelphia. 

FLASH forward to an ultra-fast new form of radiation: An experimental method delivering proton therapy radiation in just a few doses lasting mere seconds each, could be a paradigm shift in radiation therapy.

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