Carbon Ion Radiobiology

Abstract

Radiotherapy using accelerated charged particles is rapidly growing worldwide. About 85% of the cancer patients receiving particle therapy is irradiated with protons, which have physical advantages compared to X-rays but similar biological response. In addition to the ballistic advantages, heavy ions present specific radiobiological features that can make them attractive for treating radioresistant, hypoxic tumors. An ideal heavy ion should have lower toxicity in the entrance channel (normal tissue), and being exquisitely effective in the target region (tumor). Carbon ions have been chosen because they represent the best combination in this direction. Normal tissue toxicities and second cancer risk are similar to those observed in conventional radiotherapy. In the target region, they have increased relative biological effectiveness and reduced oxygen enhancement ratio compared to X-rays. Some radiobiology properties of densely ionizing carbon ions are so distinct from X-rays and protons that they can be considered as a different “drug” in oncology, and may elicit favorable responses such as increased immune response and reduced angiogenesis and metastatic potential. The radiobiological properties of carbon ions should guide patient selection and treatment protocols to achieve optimal clinical results.

Focused Ion Microbeam Irradiation Induces Clustering of DNA Double-Strand Breaks in Heterochromatin Visualized by Nanoscale-Resolution Electron Microscopy

“…Particle radiotherapy is an important treatment modality for malignant tumors due to the favorable depth-dose profile and high relative biological effectiveness within the Bragg peak [ 1 ]. Treatment planning of particle radiotherapy relies on biophysical modelling to predict the biological effects induced by diverse types of ion beams [ 20 ].…”

“…Radiotherapy is one of the major modalities for the efficient treatment of cancer. Tumor therapy with heavy ions is increasingly implemented, as dose distributions that are increasingly confined to the neoplasm and spare healthy tissues can be achieved [ 1 ]. Moreover, this dosimetric advantage is combined with the enhanced relative biological effectiveness (RBE) of this densely ionizing radiation (IR) [ 2 ].…”

Charged Particle and Conventional Radiotherapy: Current Implications as Partner for Immunotherapy

“…PRT fractionation thus far has shown excellent local control without severe toxicities [ 196 , 197 , 198 ]. For the radiobiology of protons and carbon ions, we refer to excellent reviews [ 199 , 200 , 201 , 202 , 203 ]. We will summarize here only the biological effects induced by charged particles that can modulate immune responses.…”

Physical and Biological Characteristics of Particle Therapy for Oncologists

“…radiation generally activates the genes associated with inflammatory pathways, DNA repair, and cell cycle progression, the specific genes activated by X-rays, proton, and carbon ions can be different [36]. Efforts are underway to establish cohorts of patients with prostate cancer treated at the NIRS with carbon ion therapy or proton therapy for radiogenomic studies [37].…”