FLASH radiotherapy: Research process from basic experimentation to clinical application

FLASH radiotherapy (FLASH‐RT) has gained attention as an ultra‐high dose rate RT in recent years. This treatment significantly shortens the time of RT and reduces the influence of tumor movement caused by breathing or other factors. In addition, it spares the surrounding normal tissues and organs while ensuring the anti‐tumor effect. With the efforts of scientific researchers and clinical staff, the FLASH effect has been successfully induced in electron, photon, and proton irradiation. Preliminary research has been carried out to explore its related mechanism. However, this has not yet been fully determined, although oxygen depletion was the proposed primary mechanism discovered. Due to the development of immunotherapy, studies on the involvement of the immune system in the FLASH effect have begun to attract attention. This study reviewed published experimental results to analyze and summarize the feasibility of FLASH‐RT widely used in clinical practice, and whether it could be combined with immune checkpoint inhibitors to guide therapy.