Carbon ion radiotherapy. Clinical study and future prospect

At present, most of the patients receiving carbon ion radiotherapy at National Institute of Radiological Sciences (NIRS) visit the clinic seeking this specific modality, and it is difficult to obtain consent for a randomized controlled study from these patients and it may be unnecessary to conduct a phase III trial. However, in selected tumors where the high-linear energy transfer (LET) benefit could be appreciated, we can participate in randomized studies. Finally, studies aimed at clarifying the usefulness of carbon ion radiotherapy and elucidating any advantages from hypo-fractionation should be considered. A multi-institutional prospective non-randomized concurrent phase II clinical trial is one such new approach, and it will be proposed not only to the Japanese, but also to the international community of particle therapy and radiation oncology. (author)