THE RATIONALE AND REQUIREMENTS FOR THE DEVELOPMENT OF BORON NEUTRON-CAPTURE THERAPY OF BRAIN-TUMORS

The dismal clinical results in the treatment of glioblastoma multiform e despite aggressive surgery, conventional radiotherapy, and chemother apy, either alone or in combination has led to the development of alte rnative therapeutic modalities. Among these is boron neutron capture t herapy (BNCT). This binary system is based upon two key requirements: (1) the development and use of neutron beams from nuclear reactors or other sources with the capability for delivering high fluxes of therma l neutrons at depths sufficient to reach all tumor foci, and (2) the d evelopment and synthesis of boron compounds that can penetrate the nor mal blood-brain barrier, selectively target neoplastic cells, and pers ist therein for suitable periods of time prior to irradiation. The ear lier clinical failures with BNCT related directly to the lack of tissu e penetration by neutron beams and to boron compounds that showed litt le specificity for and low retention by tumor cells, while attaining h igh concentrations in blood. Progress has been made both in neutron be am and compound development, but it remains to be determined whether t hese are sufficient to improve therapeutic outcomes by BNCT in compari son with current therapeutic regimens for the treatment of malignant g liomas.