Experience with fast neutron therapy using the texas A & M variable energy cyclotron

Between October, 1972 and September, 1973, 72 patients were treated with neutrons produced by bombarding beryllium with 16- or 50-MeV deuterons. The clinical material included 34 patients with head and neck cancer, 11 with breast carcinoma, 8 with superior sulcus bronchogenic carcinoma, and 19 with a variety of miscellaneous neoplasms. Patients were treated twice-weekly with doses calculated to include both the neutron and gamma components. Most of the patients with head and neck cancer were treated with shrinking fields to doses of 1850 radnγ/5 1/2 weeks-2350 radnγ/7 weeks with the 16-MeV beam, or 2000 radnγ/6 weeks-2400 radnγ/7 weeks with the 50-MeV beam. Preliminary evaluation indicates satisfactory local control; however, the late radiation sequelae are greater than would be expected on the basis of the acute mucosal reactions observed. A significant number of complications has developed in: 1) patients treated at higher doses, and 2) those with massive epithelial involvement even at lower doses. Consequently, doses have been reduced. With breast carcinoma, doses of 2350 radnγ/7 weeks (50 MeV) with shrinking fields have been well tolerated for this short-term followup; the local control rate has been high. Eight patients with superior sulcus tumors have been well palliated with no undue side effects. However, all were treated with conventional radiotherapy followed by a neutron therapy boost to the primary site. The miscellaneous group included a wide variety of neoplasms, the number of each type too small to draw any meaningful conclusions.