FLASH radiotherapy (FLASH-RT) is currently at the center of the attention in the radiation oncology field. The relative absence of normal tissue toxicity observed after exposure to ultra-high dose rate “FLASH”-RT compared to isodoses of conventional dose rate RT has been intensively described by multiple groups over the last eight years. Coupled to its anti-tumour efficacy described in multiple preclinical models, veterinary clinical trials and a first compassionate use of FLASH-RT on a human patient, this phenomenon is now known as the “FLASH effect”. Most of these studies conclude that FLASH-RT has the potential to increase the therapeutic ratio of RT and that its clinical translation could lead to major benefits for the patients. But is this new radiotherapy modality ready to be used in the clinics, and will FLASH-RT save us all by 2030?
New paradigms usually come with new challenges, and FLASH-RT follows this rule. Importantly, the FLASH effect could not have been predicted by classic radiobiology models and raises important questions at the biology level. So far, no underlying mechanism has been identified to explain the FLASH effect, and multiple hypothesis are still under investigation. As multiple teams are already planning, designing, or even performing the first clinical trials, the FLASH-RT technology is not yet ready to be routinely used in the clinics. Many technological and physical aspects need to be developed, adapted, or improved, such as: IGRT, TPS or dosimetry techniques, to insure a safe and efficacious clinical translation.
For these reasons, the question is still open. FLASH-RT has the potential to significantly improve radiotherapy treatments, not only by increasing the therapeutic ratio, but also by bringing new possibilities such as motion management, faster treatments, or new treatment combinations. On the other hand, this technology is not quite ready to be routinely implemented in the clinics, and its modalities of implementation (beam type, treatment schedule, indications…) are yet to be defined. Will FLASH-RT save us all, or at least become a new tool within the radiotherapy techniques that will save us all? To answer this question over the upcoming years, multidisciplinary teams must work together and bring solid new models, tools, and results.