• Flash ultra-high dose rate therapy enabled by Varian proton and planning technologies
• Collaboration between Varian and leading institutions drives progress toward next-generation cancer treatments
• Flash delivers treatment over 100 times faster than conventional radiation therapy

Varian, a Siemens Healthineers company, has announced the successful completion of enrollment and treatment in its FAST-02 (Flash Radiotherapy for the Treatment of Symptomatic Bone Metastases in the Thorax) clinical trial. The FAST-02 study targets painful bone metastases in the thoracic region and represents a significant step toward bringing this investigational radiotherapy treatment into clinical practice.

The trial was conducted at Cincinnati Children’s Hospital/UC Health Proton Therapy Center and enrolled 10 participants. It focused on evaluating treatment-related side effects and the efficacy of treatment, which was assessed using trial participants' reported pain relief. FAST-02 builds upon findings from Varian’s FAST-01 trial, which evaluated clinical workflow feasibility of Flash therapy and treatment-related side effects for participants with bone metastases in the extremities. The trial is led by Principal Investigator John Perentesis, M.D., Professor and Director, Cancer and Blood Disease Institute, Cincinnati Children’s Hospital, and lead Co-Investigator Emily Daugherty, M.D., Associate Professor of Radiation Oncology, University of Cincinnati Cancer Center.

Flash therapy delivers treatment at ultra-high dose rates in typically less than one second – over 100 times faster than conventional radiation therapy—and has demonstrated potential in preclinical studies to reduce damage to surrounding healthy tissues while maintaining effective tumor control.

“Completing treatments for FAST-02 is a pivotal and progressive step in our effort to establish the safety and effectiveness of Flash radiotherapy,” said John Perentesis, M.D., Professor and Director, Cancer and Blood Disease Institute, Cincinnati Children’s Hospital Medical Center (CCHMC). “This trial helps lay the groundwork needed to move Flash into more advanced clinical settings—an innovation that could redefine radiation oncology and meaningfully improve patient outcomes.”

As part of the FAST-02 trial, Varian’s ProBeam proton therapy system was modified to enable ultra-high dose rate delivery for Flash treatments. In parallel, the Eclipse treatment planning system was enhanced to support planning for Flash therapy. Varian is advancing Flash therapy as an integrated system, encompassing planning, quality assurance, and treatment delivery technologies.

“The integration of treatment and planning represents a major technological achievement,” said Anthony Mascia, executive director and director of medical physics of the CCHMC Proton Therapy Center. “From a physics standpoint, we’re pushing the boundaries of both planning and delivering ultra-high dose rates, and we’re doing it safely.”

OSF HealthCare, a multi-site healthcare system with locations across Illinois and Michigan, collaborated in the trial and referred participants for enrollment.

James McGee, MD, founding director of the OSF Cancer Institute, stated: “We’re proud to have supported the FAST-02 trial. It is rewarding to contribute to research that further advances Flash therapy.”

Added Deepak “Dee” Khuntia, MD, senior vice president and chief medical officer at Varian: “This is an exciting time for radiation oncology; completing enrollment in FAST-02 underscores our commitment to develop the evidence needed to advance technologies that have the potential to transform the future of cancer care. We are proud to collaborate with institutions that share our vision for patient-centered innovation.”

Now that participant treatment is complete, data analysis of the results will inform future clinical studies and further evaluation of the potential of Flash therapy across broader treatment applications.

For information about the FAST-02 clinical trial, go to: Study Details | FLASH Radiotherapy for the Treatment of Symptomatic Bone Metastases in the Thorax | ClinicalTrials.gov

© 2025 VARIAN MEDICAL SYSTEMS, INC. All trademarks are the property of their respective owners.

CAUTION: The Flash-enabled ProBeam system is an investigational device and is limited by United States law for investigational use.

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About Varian

At Varian, a Siemens Healthineers company, we envision a world without fear of cancer. For more than 75 years, Varian has developed, built, and delivered innovative technologies and solutions that help care providers around the globe treat millions of patients each year. Today, as a Siemens Healthineers company, we support every step of the cancer care journey – from screening to survivorship. From advanced imaging and radiation therapy to comprehensive software and services, to interventional radiology, we are harnessing the power of our perspective while also pursuing clinical research to create a more efficient, and more personalized care pathway. Because, for cancer patients everywhere, their fight is our fight. For more information, visit http://www.varian.com.

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