Early assessment of normal tissue tolerance of fast neutron beam radiation therapy

Between September 10, 1973 and May 20, 1975, 94 selected patients were treated with fast neutron beams generated by bombarding an "intermediate" beryllium target with 21 MeV deuterons. The clinical material included: 58 patients with head and neck cancers; 27 patients with cerebral glioblastoma multiforme; and 9 patients with a variety of other neoplasms. Of the 67 patients treated only with neutron beams, 31 received two increments per week and 36 received three increments per week. The calculated doses in most patients were 1800 rad n gamma (neutrons + gamma components) delivered in 6 weeks. Seventeen patients were treated with two increments of neutron beams and three increments of 60Co photons weekly to calculated total doses of 780-1050 rad n gamma + 3360-3780 rad 60Co gamma delivered over 50-54 days. Ten patients were treated with neutron bean "boosts" of 300-900 rad n gamma in three to seven increments over 8-23 days following conventional radiation therapy. Treatment has been well tolerated, with only 9 of 94 patients not completing the anticipated course. In three of these, treatment was dixcontinued because of intercurrent problems. Except for those patients with glioblastoma multiforme, treatment complications have not been dose-related. In four patients, complications probably were related to persistent cancer. Neutron beam irradiaiton may have been a factor in the neurologic deterioration of five patients with glioblastoma multiforme who did not complete treatment.