Boron neutron capture therapy: Clinical brain tumor studies

Since 1968, we have treated 149 patients andperformed boron-neutron capture therapy (BNCT) on 164 occasionsusing 5 reactors in Japan. There were 64patients with glioblastoma, 39 patients with anaplastic astrocytomaand 17 patients with low grade astrocytoma (grade1 or 2). There were 30 patients withother types of tumor. The overall response ratein the glioma patients was 64%. Seven patients(12%) of glioblastoma, 22 patients (56%) of anaplasticastrocytoma and 8 patients (62%) of low gradeastrocytoma lived more than 2 years. Median survivaltime of glioblastoma was 640 days. Median survivaltimes of patients with anaplastic astrocytoma was 1811days, and 1669 days in low grade astrocytoma.Six patients (5 glioblastoma and one anaplastic astrocytoma)died within 90 days after BNCT. Six patients(two glioblastoma and four anaplastic astrocytomas) lived morethan 10 years. Histological grading, age of thepatients, neutron fluence at the target point andtarget depth or size of the tumor wereproved to be important factors. BNCT is aneffective treatment for malignant brain tumors. We arenow able to radiate the tumor more correctlywith a high enough dose of neutron beam,even if we use thermal neutron beam.