The Use Of Iridium-192 At Radiation Treatment Of Vaginal Cancer With Radiobiological Accompaniment

Increasing of efficiency of chemoradiation therapy (CRT) of secondary vaginal cancer (metastatic forms) continues to remain an object of broad discussion. We have performed complex conservative treatment in 98 patients with II–III stages of secondary metastatic vaginal cancer, T2-3N0-1M0. Average age of patients was 57,3±5,2 years old. 3 groups were formed depending on the source (¹⁹²Ir, ⁶⁰Co), radiation regimen, radiation activity of HDR (high dose rate — higher than 12 Gy/hr) brachytherapy in the background of chemosensibilization agents (oral fluoropyrimidines, platinum-based drugs). 2 study groups included 30 patients, who underwent HDR brachytherapy with ¹⁹²Ir by single focal dose of 3 Gy x 3 times per week and 33 patients who underwent HDR brachytherapy with ¹⁹²Ir by single focal dose of 5 Gy x 2 times. Control group included 35 patients who received HDR brachytherapy with ⁶⁰Co by single focal dose of 5 Gy x 2 times per week. Total focal dose of combined radiation therapy was up to 80–90 Gy to tumor focality and 44–46 Gy to areas of regional metastases. Radiobiological accompaniment included performing in vivo cytogenetic monitoring of lymphocytes in peripheral blood and comparative analysis of genotoxicity of different brachytherapy regimens. Analysis of direct results of efficiency of the usage of HDR brachytherapy with ¹⁹²Ir different regimens comparatively to patients of control group, who received HDR brachytherapy with ⁶⁰Co, and dynamic surveillance data for 3 months showed, that positive tumor response (total + partial regression) after chemotherapy course increased to 20,3 % and 17,9 % in secondary metastatic vaginal cancer patients in study groups comparatively to the usage of HDR brachytherapy with ⁶⁰Co. Toxic effects of treatment according to the number and degree of their manifestations in study groups of patients were no different from control group and did not exceed II grade. Therefore, proposed methods of high-energy brachytherapy in patients with secondary (metastatic) vaginal cancer are effective and do not have excessive toxicity. Radiobiological studies provide an opportunity to determine previous individual radiosensitivity of the patient's organism based on the level of chromosomal aberrations of peripheral blood lymphocytes. (author)