Samsung Seoul Hospital has moved closer to clinical application of FLASH, a high-dose radiation therapy, after being the first private hospital in Korea to introduce proton therapy equipment.
The hospital announced on the 13th that a research team led by Professors Han Young-yi and Choi Chang-hoon of the Department of Radiation Oncology, along with Dr. Lee Sung-eun, confirmed through preclinical studies that proton-based FLASH therapy protects surrounding normal tissue in the lungs.
Proton therapy is a form of radiation treatment that accelerates protons to near light speed and projects energy beams onto cancerous tissue inside the patient's body. Like heavy ion therapy, it utilizes the Bragg peak phenomenon, where particle beams accelerated to a certain speed release energy at the moment they strike cancer cells and then dissipate. This enables precise targeting of cancer cells without destroying surrounding normal cells. The difference is that proton therapy uses hydrogen particles while heavy ion therapy uses heavier carbon particles.
FLASH is a next-generation radiation therapy technology that intensively delivers high-dose radiation of 40 Gray (Gy) or more per second in less than one second. When applied to existing proton therapy, it can maximize protection of normal organs by reducing radiation exposure time while maintaining cancer-killing capability.
Samsung Seoul Hospital, noting that FLASH—regarded as a future technology that could dramatically improve cancer treatment—remains in early clinical research stages globally, has been conducting joint research on the technology with Japan's Sumitomo Heavy Industries. In this study, researchers used their own experimental model to locally irradiate lung tissue with protons equivalent to 60 Gy, comparing conventional treatment with FLASH therapy. Unlike previous FLASH studies targeting the entire lung, this research limited the irradiation area similar to actual cancer treatment. Conventional treatment delivered 2 Gy per second over approximately 30 seconds, while FLASH therapy increased the speed 250-fold, delivering 500 Gy per second over approximately 0.12 seconds.
According to the research team, conventional-speed irradiation caused severe pulmonary fibrosis, where lung tissue hardens, along with inflammatory reactions. FLASH therapy significantly reduced these side effects. Tissue recovery was also much faster. Dermatitis symptoms such as skin thickening and necrosis were significantly reduced compared to conventional treatment. The study also identified biological mechanisms by which FLASH therapy suppresses inflammatory substance production in lung tissue and reduces oxidative stress, thereby preventing DNA damage to normal cells—considered a key achievement.
Samsung Seoul Hospital has performed approximately 100,000 proton therapy treatments for some 8,000 patients over ten years since opening its Proton Therapy Center. Last year, the hospital successfully developed precision dose assessment technology, an essential foundation for clinical application of FLASH.
"This study suggests that proton FLASH therapy could become a new breakthrough in treating intractable cancers such as lung cancer," Professor Han said. "We will continue research to lead domestic particle beam therapy and provide safer, more effective treatments for patients."
The research was conducted as part of the "Future Technology Research on Proton Irradiation for Cancer Treatment Innovation" under the Ministry of Science and ICT's "Radiation-Based Future Innovation Foundation Technology Research Project." It was published in the latest issue of the British Journal of Radiology, an authoritative international journal in the field of radiology.