The use of neutrons in cancer therapy: a historical perspective through the modern era.

The fields of boron neutron capture therapy (BNCT) and fast neutron radiotherapy are surveyed starting with the early clinical work that began shortly after the discovery of the neutron by Chadwick in 1932. The evolution of each field is described and the current status in regards to accepted clinical indications and ongoing research areas summarized. BNCT remains a research area but a discussion is given of current efforts to design and construct non-reactor-based epithermal neutron sources to deploy this technology to major medical centers if the clinical research proves successful. Fast neutron radiotherapy is a mature field with selected clinical indications for locally advanced salivary gland tumors and inoperable sarcomas of bone and soft tissue. The current status of clinical trials for locally advanced prostate cancer and other tumors is reviewed. Ongoing areas of research in the field of fast neutron radiotherapy are described.