Abstract
Particle therapy, such as proton therapy and carbon ion therapy, is capable of delivering high-dose radiation to tumors while minimizing the dose delivered to organs at risk because it emits maximum energy just before stopping in the deep portion of the body. Carbon ion therapy, which efficiently induces DNA double strand break due to its high ionizing density, is expected to be effective even for photon-resistant tumors. While there is a lot of evidence on the usefulness of particle therapy for chordoma/chondrosarcoma of the skull base, there is little evidence for sarcomas of the head and neck. Since May 2016, the nationwide unified dose-fractionations (unified treatment protocols) for proton therapy and carbon ion therapy have been used to generate evidence together with all-case registration. Patients who cannot be treated with other treatment options are often referred to particle therapy centers and we have to treat them even if a certain level of adverse events can be predicted. As a result, severe adverse events are sometimes experienced. Because little is known about combinational effects of particle therapy and new drugs such as molecularly targeted drugs, even if administered metachronously, careful handling is needed.
