The Effects of Boron Neutron Capture Therapy on the Lungs in Recurrent Breast Cancer Treatment

Boron neutron capture therapy (BNCT) has predominantly been performed for brain tumors or head and neck cancers. Although BNCT is known to be applicable to breast cancer, it has only been performed in a few cases involving thoracic region irradiation with reactor-based BNCT systems. Thus, there are very few reports on the effects of BNCT on the thoracic region and no reports of BNCT for breast cancer with accelerator-based BNCT systems. This paper introduces the world's first clinical study employing an accelerator-based BNCT system targeting recurrent breast cancer after radiation therapy. We aim to assess the efficacy and safety of BNCT, focusing on the dose response in the thoracic region, especially concerning the potential for radiation pneumonitis. Preliminary findings from the first three cases indicate no evidence of radiation pneumonitis within three months post treatment. This study not only establishes a foundation for novel breast cancer treatment options but also contributes significantly to the field of BNCT in the thoracic region.