Flash radiotherapy, an innovative approach delivering radiation in less than a second, is emerging as a potential game-changer in cancer treatment, offering the promise of safer and more effective care. This ultra-fast cancer treatment aims to revolutionize how tumors are targeted, potentially minimizing harm to surrounding healthy tissue.
The FLASH Effect
Traditional radiotherapy, a cornerstone of cancer treatment, involves exposing tumors to radiation over several minutes across multiple sessions. While effective, this method often damages healthy tissue, especially in sensitive areas. Flash radiotherapy flips this script by delivering ultra-high doses of radiation in milliseconds. This induces the FLASH effect, reducing harm to normal tissue while still killing cancer cells at the tumor site.
Marie-Catherine Vozenin first demonstrated this ultra-fast cancer treatment in the early 2010s, with animal studies showing remarkable success. Experiments revealed that Flash eliminates tumors and significantly reduces harmful side effects, such as impaired organ function or developmental delays in pediatric patients. The ultra-fast approach allows oncologists to use higher doses of radiation, increasing the chances of destroying stubborn cancers.
Clinical Trials and Early Results
Human trials are already underway, showing promise for treating metastatic cancers and complex tumors, like glioblastomas and recurrent head-and-neck cancers. These conditions are notoriously challenging, with limited treatment options and significant risks of damage to healthy tissue. A first-in-human trial in a small group of patients with metastatic cancer found the treatment safe and effective for pain relief.
Emily C. Daugherty, MD, lead author of a study and an assistant professor of clinical radiation oncology at the University of Cincinnati Cancer Center, stated in 2022, "Our study shows FLASH radiotherapy with protons is a practical modality to reduce pain. It deserves further exploration because of its potential to decrease the side effects associated with conventional radiation treatments."
John Breneman, MD, FASTRO, principal investigator on the trial and a professor of radiation oncology and neurosurgery at the University of Cincinnati Cancer Center, noted, "Because FLASH radiotherapy is given at ultra-high dose rates, it appears to cause less normal tissue injury. This offers the possibility of delivering larger doses of radiation – which could result in higher cure rates for patients with resistant tumors – without increasing side effects."
Technological Hurdles and Future Directions
Proton therapy, a type of particle-based radiotherapy, has emerged as a frontrunner during these Flash trials. Protons penetrate deep into the body, making them ideal for treating internal organs without affecting nearby healthy tissue. However, researchers are also exploring alternatives like electrons and carbon ions to expand the applications.
Currently, the biggest hurdle is accessibility. Flash treatments require advanced particle accelerators, which are large and costly—there are only 14 facilities in the world capable of running one. Major technological advances are needed to enable the generation of FLASH photons, and potentially of protons, VHEE and heavy ions. If smaller, more affordable accelerators can be developed, this ultra-fast cancer treatment could become more widely available.
Researchers are still working to fully understand why FLASH RT kills tumors with fewer side effects compared to conventional radiation. Further research is needed to determine the biological mechanisms driving the FLASH effect.
