Boron-Neutron Capture Therapy vs. Photon Beam for Malignant Brain Tumours — 12 Years’ Experience

Slow neutron capture therapy is intended to irradiate tumor tissue selectively with heavy particles produced by the neutron-capturing reaction of Boron-10, Lithium-6 and certain other nuclides (6, 9, 16, 19, 34). In early trials between 1953 and 1961 p-carboxyphenyl boronic acid or sodium perhydrodecaborate (29, 30), and more recently, since 1968, mercaptoundecahydrododecaborate have been used for brain tumour treatment (8,28). Brain tumours are most suited to this type of therapy, because of the so-called Blood-Brain Barrier phenomenon which allows a discriminative transport of the neutron-capturing isotope into the tumour tissue but not into the surrounding brain matter, yielding a large Tumour/Brain ratio in isotope concentration (1, 4, 20). After the first trial of Boron-Neutron Capture Therapy in Japan in 1968, 44 malignant brain tumours were treated with neutron capture. Thirty-two of the 44 were treated with neutron capture alone, but 12 others were treated only after the failure of preceding conventional radiotherapy with photon. The clinical results were compared with that of 90 patients treated with photon. Most of the photon-treated patients with malignant gliomas underwent adjuvant therapy with chemo- or immuno-therapeutic agents. Tumours with better prognosis with conventional radiotherapy are excluded.