シンポジウム ホウ素中性子捕捉療法の獣医学分野への適応拡大に向けて -取り組むべき課題と異分野融合研究の可能性-

Abstract

The Institute for Integrated Radiation and Nuclear Science, Kyoto University has been conducting clinical research on Boron Neutron Capture Therapy (BNCT), a type of radiotherapy, with neutrons from research reactors to treat malignant brain tumors, intractable head and neck tumors, malignant melanoma and other tumors that are usually resistant to X-rays, multiple liver tumors, mesothelioma, and other tumors that are difficult to treat with other types of radiation or particle therapy. In recent years, we have been conducting clinical research using neutrons from research reactors for malignant brain tumors, intractable head and neck tumors, tumors resistant to conventional X-rays such as malignant melanoma, multiple liver tumors, mesothelioma, and other tumors that are difficult to target with other radiation and particle therapy. In recent years, we have succeeded in developing an irradiation system using an accelerator neutron source that can be installed in a hospital, and several medical institutions have introduced the system, conducted clinical trials, and in March 2020, we obtained approval for the manufacture and sale of medical devices and drugs for head and neck cancer. It is expected to be applied to more diseases in the future. At present, the indication of BNCT is limited to malignant tumors located shallowly from the body surface because the neutron beam used in BNCT does not reach deep into the body, but it is possible to administer a sufficient amount of neutrons to malignant tumors in any part of the body in the size of companion animals such as dogs and cats. In addition, it is possible to make a large difference in the dose administered at the cellular level between tumor cells and normal tissue cells. In addition, BNCT is classified as heavy particle therapy and is expected to be effective in treating sarcoma, which is considered to be one of the most common malignant tumors in companion animals. This paper is a summary of the presentation "Toward the Expansion of Boron Neutron Capture Therapy to the Veterinary Field: Issues to be Tackled and the Potential for Interdisciplinary Research" held on March 4, 2021. We believe that we were able to exchange opinions on various issues regarding the application of BNCT to companion animals using a small accelerator BNCT irradiation system that can be installed in a hospital, as well as the possibility of interactive academic interdisciplinary research in the fields of human radiation oncology and veterinary medicine. We hope that this paper will be useful to all concerned in promoting research.

京都大学複合原子力科学研究所では、放射線治療の1つである、ホウ素中性子捕捉療法（Boron Neutron Capture Therapy, 以下BNCT）研究を、研究用原子炉からの中性子を利用して、悪性脳腫瘍、難治性頭頸部腫瘍、悪性黒色腫等の通常X線に抵抗性の腫瘍、多発性肝腫瘍、中皮腫等、他の放射線・粒子線治療では狙いにくい腫瘍を対象として臨床研究を実施してきました。近年では、病院併設可能な加速器中性子源を用いた照射システムの開発に成功し、複数の医療機関が導入、治験を実施、2020年3月頭頸部がんを対象とした医療機器・医薬品の製造販売承認を獲得しました。今後より多くの疾患に対して適応されることが期待されています。BNCTで使用する中性子線は体深部に十分量が到達しない点から、現時点において、BNCTの適応は体表から浅い位置の悪性腫瘍に限られる一方、イヌ、ネコなどの伴侶動物の大きさであれば、どの部位の悪性腫瘍へも十分な中性子量の投与が可能であり、また腫瘍細胞と正常組織細胞の間に､細胞レベルで投与する線量に大きな差を付けることが可能で、原則、1日1回の照射で治療終了です。また、BNCTは重粒子線治療に分類され、伴侶動物の悪性腫瘍で多いとされる肉腫に対して治療効果が期待できます。本紙は、令和3年3月4日に開催した、「ホウ素中性子捕捉療法の獣医学分野への適応拡大に向けて-取り組むべき課題と異分野融合研究の可能性–」の発表をまとめました。病院に併設可能な小型加速器BNCT照射システムを用いた伴侶動物に対するBNCTの適応について、諸課題と併せヒトの放射線腫瘍学と獣医学分野における双方向性の学術的な異分野融合研究の可能性について意見交換が出来たと考えています。本紙が関係者の皆様に、研究推進としてお役に立てれば幸いです。