[Fast neutron radiotherapy at NIRS, indication and prospects].

Eleven hundred and seventy one patients, 921 previously untreated and 250 recurrent, have been treated with 30 MeV (d-Be) fast neutron beam between 1975 and 1984 at NIRS. Some trends have been identified: non-randomized results have been at least as good as those of photons in carcinomas such as: supraglottic carcinoma in the larynx, pancoast type tumor of the lung, malignant melanoma of the skin and so on. Randomized results with mixed beam studies for carcinoma of the uterine cervix have indicated no significant advantages against those of photons. Treatment technique for the beam concentration must be improved to demonstrate the merit of neutrons in the next step.