Cytogenetic effects in cancer patients lymphocytes depending on the radiation source and the locality of radiation exposure in experiment ex vivo

Aims: Estimation of the cytogenetic lesions yield and their distribution among cells in donor lymphocytes of cancer patients with different tumor localizations depending on the source of radiation and the locality of radiation exposure in a therapeutically significant dose in ex vivo experiment. Methods: Cytogenetic analysis was performed in lymphocytes of 30 oncogynecological patients, lung cancer patients and head and neck cancer patients before the start of radiation treatment. Whole peripheral blood was irradiated at 2 Gy dose with a further simulation of partial body irradiation using gamma-irradiation 60 Co on the ROKUS-AM and megavolt irradiation on the linear accelerator Clinac 600C. Results of research: An increase of radiation-specific chromosome damage frequency after gamma- and megavolt irradiation of cancer patients’ lymphocytes at 2 Gy dose was shown. With the absence of dependence on the tumor localization the statistically significant excess of the chromosome exchanges level due to irradiation on linear accelerator in compare with gamma-irradiation was found. At 2 Gy dose point with a simulation of partial body irradiation a similar dependence on the applied source was observed. So, the increase of the chromosome type aberrations level was due to 2,5-fold increase of the dicentric and ring chromosomes number under the gamma-irradiation and 5-fold under megavolt irradiation. For local irradiation simulation for both sources the chromosome aberrations level significantly exceeded the values of the zero point, and the dicentrics distribution among cells was over-dispersed according to Poisson statistic. Conclusion: Cytogenetic studies in ex vivo experiment showed that in donors’ lymphocytes, regardless of the tumor location, megavolt irradiation demonstrated a more genotoxic effect in compare with gamma-irradiation. The data obtained indicated that the proposed test experiment of ex vivo irradiation with partial body radiation simulation can be successfully used to detect the fact of irradiation and to confirm, if present, its locality. The study results will contribute to the improvement of the radiobiological basis of cancer patients’ radiation treatment and can be of use for the development of approaches to the individualization of therapeutic irradiation