Kazuyo IGAWA
Neutron Therapy Research Center, Okayama University, Okayama, Japan
In recent years, high-precision radiotherapy for cancer has been established with the development of therapeutic equipment that generates various types of radiation, such as X-rays, proton beams, heavy particle beams, and neutron beams, as well as radiation irradiation methods to reduce the dose of radiation to surrounding normal tissues. As one of the radiation therapies, Boron neutron capture therapy (BNCT) is expected to improve treatment outcomes and reduce side effects. BNCT is a unique binary therapy based on the idea of selectively delivering boron compounds into tumour tissue, which is subsequently irradiated with neutrons. These neutrons are captured by boron, which is followed by the emission of alpha particles and recoil of the lithium nucleus, both with very high energy transfer within extremely short stopping distances, comparable to the size of a single cell. Both the intracellular high biological effectiveness and strictly localized tumour cell damage at the cellular level are the major advantages of BNCT in clinical therapy.
Since 1951, BNCT has been performed mainly at research reactors, and in the last two decades, more than 1000 patients worldwide have been treated at these facilities and significant progress. However, many of these reactors have been shut down or have discontinued their BNCT-related activities, in particular, due to the difficulty of combining a reactor environment with clinical requirements. Presently only four reactors continue to offer BNCT as a possible cancer treatment, including Tsing Hua open-pool reactor (THOR) in Taiwan.
The first reactor-based BNCT for head and neck cancer was conducted by an oral maxillofacial surgeon, Dr. Kato, Osaka University, in 2001. Instead of reactor-based BNCT, the accelerator-based BNCT for head and neck cancer was approved in Japan in 2020, then over 100 head and neck cancer patients were treated at Osaka Medical and Pharmaceutical University, Osaka, and Southern Tohoku Hospital, Fukushima. I will introduce you to the current status of BNCT worldwide.
