[The reaction of tumors and normal tissues to therapy with fast neutrons from the U-120 cyclotron].

In the present information results of clinical studies are represented to show the effectiveness of therapy with 6.3 MeV fast neutrons in 45 patients with superficial tumors in head and neck area. The reaction of tumor and of normal tissue was studied in dependence on different physical and biological factors. Two variants of neutron therapy planning were estimated by means of mathematical models of a factor of time-dose-fractionation for neutron (TDFN) from clinical point of view. Results of changes in oxygen-tension within the tumor are represented in 20 patients with metastases in cervical lymph-nodes during neutron therapy. The obtained data show a correlation of regression and reoxygenation rate of the tumor to its initial volume. The reaction of the tumor in therapy with fast neutrons was studied in dependence on its morphological structure. Complete regression of epidermoid and nonepidermoid cancer types was seen in 42 or 89% of the cases. With corrections for adipose tissue and the extent of dose fraction of fast neutrons the clinical test of the mathematical model of TDFN-factor made discernible that the reaction of normal tissue can be prognosticated quite exactly by means of this model in neutron therapy.