Advances in Radiation Biology of Particle Irradiation

The increasing number of centers providing proton or carbon beam therapy underlines the growing importance of charged particle therapy within the spectrum of cancer radiotherapy. Whereas protons are more widely used around the world, carbon ions, which are known to bear a higher efficacy as compared to protons, are still neglected to some extent, especially due to a lack of clinical data on adverse side effects. Yet, an increasing amount of clinical data indicates the distinguished efficacy of carbon ion therapy. Notwithstanding, the radiobiological mechanisms of particle radiation are not completely understood and lag behind advances in technology, which potentially enable new therapy regimens. However, an increased knowledge is required for their application with maximal benefit and sufficient risk estimation. Differential gene expression, distinct molecular mechanisms and signal pathways in the radiation response, and systemic effects, such as increased immunogenicity, and the possibilities of combined treatments arising from them, are important fields of particle radiobiology in which new discoveries and advances have occurred. These aspects are contemplated with respect to an individualization of radiotherapy; radiation type and treatment regimen might be chosen on the basis of the radiosensitivity of the individual and the cancer type. Here, we provide an update on a few recent findings and advances in particle radiobiology. A comprehensive essay on the basics of particle radiobiology is beyond the scope of this article. The focus is directed on a few subjects currently undergoing intense study and which are of current interest with respect to advances in therapy.