Chromosome type aberrations outcome in oncogynecological patients due to radiation therapy on ROCUS-AM and linear accelerator Clinac 600C

Abstract

Aims: The detection of chromosome type aberrations outcome in oncogynecological patients during radiation therapy depending on the irradiation regime.Methods: The group of 36 oncogynecological patients was examined before treatment, in the middle and at the end of external gamma-radiotherapy 60Со on ROCUS-AM and megavolt therapy on linear accelerator Clinac 600C. Lymphocytes were cultivated by conventional technique during 50 – 54 hours. Chromosome type aberrations were detected with the classical cytogenetic analysis.Results of research: The chromosome type aberrations changes in lymphocytes of oncogynecological patients during external gamma-radiotherapy 60Со on ROCUS-AM and megavolt therapy on linear accelerator Clinac 600C were demonstrated. The excess of chromosome type cytogenetic damage over spontaneous level was shown in patients before treatment. Quite monotonic increase of chromosome type aberrations frequency from the start to the end of radiotherapy course in both groups was found. However the pace of chromosome type aberrations increase was different depending on the irradiation regime and more pronounced in oncogynecological patients undergoing gamma-therapy 60Со. The range of cells with unstable chromosome aberrations expanded during the radiotherapy course. In the middle of the radiotherapy cells with 1 – 7 aberrations per cell in both groups were observed. At the end the number of damages per aberrant cell varied from 1 to 11 in ROCUS-AM patients and from 1 – 9 in patients after megavolt therapy on a linear accelerator. The distribution of the chromosome type aberrations among cells was found to be over-dispersed according to Poisson statistic in both studied groups at the middle and at the end of the radiotherapy course.Conclusion: The study of the radiation-induced aberrations revealed the similar and different features of cytogenetic damages accumulation in patient groups depending on the regime of irradiation. The study results revealed the absence of the expected larger genotoxic effect on the patients’ lymphocytes due to treatment on a linear accelerator in comparison with the ROCUS-AM, despite of the difference in the exposure energy. The data obtained are particularly important for a correct assessment of the local fractionated irradiation effects in the non-tumor patient cells