Results of the combined photon-neutron therapy in the conditions of escalation of a dose of neutrons generally a course of the combined photon-neutron therapy

Purpose: optimization of the combined photon-neutron therapy at patients with malignant tumors of the head and neck (HNT) in radical and palliative programs of radiation therapy. Materials and methods: 351 patients with malignant tumors of the head and neck were included in research. The first group consisted of patients with the contribution of neutrons of 2.4 Gy (n = 320). The second group included patients with the contribution of neutrons of 4.8 Gy (n=31). Distribution of patients into groups was carried out accounting to the contribution of neutrons to the general course of the combined photon-neutron therapy. Results: По окончанию расширенной биологической дозиметрии НГ-12И получено, что коэффициент ОБЭ нейтронного излучения, генерируемого установкой НГ-12И, при остром воздействии составил 1,53; при фракционированном воздействии - 3,06. At the end of the expanded biological dosimetry of NG-12I it was established that the coefficient of OBE of the neutron radiation generated by the NG-12I installation during acute irradiation was 1,53; and during fractioned irradiation it was 3,06. The obtained data allowed to define the total and single doses of neutron therapy during the work on NG-12I for difficult clinical situations in tumors of the head and neck. The clinical approbation of this technique was carried out. The dynamic supervision over patients of the second group within three years revealed increase of overall three-year survival by 7.3% (93.6% against 86.3% in SFNT group with a contribution of 2.4 Gy). The difference was not statistically significant. The comparative analysis of radiation complications in two groups showed that the frequency of early radiation injuries of skin and mucous membranes of 1, 2 and 3 degrees were: in the second group 38.6%, 29.1% and 25.9%, in the first group 75.62%, 7.86%, and 3.72%, respectively. Thus, the frequency of the second and third grade early radiation damage of the skin and mucous membranes was significantly different in those groups: of 55% against 11.5%. In 3.2% of cases the 2d grade perichondritis was diagnosed. In 3.2% of cases the ulcerative perichondritis was diagnosed 3 months after the end of treatment (the 3d grade damage). In the second group the frequency of late radiation damages was 6.4% higher. Distinctions weren''t statistically significant (р>0,05). Conclusion: The combined photon-neutron therapy with increase in a contribution of neutrons to the general course of radiation therapy allows to achieve good local control, to reduce number of local recurrences, and as a result, to improve quality of life and survival in patients with the adverse clinical prognosis in various forms of HNT with moderate toxicity.