Local control of subcutaneous murine melanoma xenografts in nude mice by neutron capture therapy.

The systemic administration of enriched [10B]D,L-p-boronophenylalanine results in the selective uptake of boron by Harding-Passey melanoma xenografts in the nude mouse model. The boron-10 located in the tumour cells acts as a radiation sensitizer for thermal neutron irradiation. The nude mouse model can be successfully used to demonstrate that regression and local control of melanoma can be achieved by neutron capture therapy. Control is a manifestation of the high linear energy transfer radiation released after neutron capture by boron-10, and does not result from an equal fluence of neutrons alone. Histological examination of remnant tumour beds 300 days after treatment shows the presence of isolated melanoma cells. However, these cells are few in number and appear incapable of division.