Shaping the future of radiotherapy: the role of electron beams and flash techniques

Relevance. Radiation therapy (RT) remains a cornerstone of oncology, offering targeted treatment for various cancers. With its roots tracing back to the discovery of X-rays by Wilhelm Röntgen and radium research by Marie Curie, RT has evolved into a sophisticated field encompassing a range of techniques. However, the rising global cancer burden highlights the need for continuous advancements to enhance efficacy while minimizing collateral damage. Traditional modalities such as X-rays and gamma rays have established their role in cancer treatment, yet they often lead to unintended damage to healthy tissues. Electron therapy has emerged as a promising alternative, leveraging distinct dosimetric properties that enable precise targeting with limited penetration depth. Low-energy electron beams are ideal for superficial tumors, while Very High-­Energy Electrons (VHEEs) extend the reach to deep-seated tumors, rivalling proton and heavy-ion therapies. Furthermore, the FLASH effect — a phenomenon reducing healthy tissue toxicity at ultra-high dose rates, offers a breakthrough in electron therapy, improving patient quality of life. Despite these advancements, challenges persist. Limited penetration depth, secondary radiation from bremsstrahlung, and complexities in dose delivery systems constrain broader clinical adoption. Moreover, unresolved biological uncertainties, such as variability in relative biological effectiveness (RBE), necessitate further research. This review explores the historical evolution, unique benefits, and limitations of electron therapy compared to traditional modalities. It highlights advancements like VHEEs, FLASH therapy, and hybrid approaches, while addressing technological challenges and the future potential of electron beams in oncology. Conclusion. Integrated with recent technological breakthroughs, electron therapy may redefine the future of radiotherapy by offering safer, more precise, and individualized cancer treatment strategies.