RADIATION-INDUCED DESTABILIZATION OF THE BLOOD LYMPHOCYTES' GENOME IN CANCER PATIENTS DEPENDING ON THEIR INDIVIDUAL RADIOSENSITIVITY.

OBJECTIVE

determination of the patterns of chromosome aberration formation in peripheral blood lymphocytes ofcancer patients with different types and tumors' localization, taking into account the individual radiosensitivity ofthe organism.

METHODS

Test system of peripheral blood lymphocyte culture from patients with tumors of various types and locations and conditionally healthy individuals. Metaphase analysis of chromosome aberrations was performed in thefirst mitosis. Individual radiosensitivity was determined based on test irradiation of lymphocytes in the G2 periodof the mitotic cycle. Quantitative assessment of the chromosomal damage formation and construction of standardcalibration dose curves based on cytogenetic indicators in irradiated blood lymphocytes were performed using thespline regression model.

RESULTS

In primary cancer patients with different tumor localization, the spontaneous level of chromosome aberrations in peripheral blood Tlymphocytes is already compromised before the start of radiation therapy, and thereforethe cells can only be defined as conditionally healthy (nonmalignant). At the same time, the average frequency ofchromosome aberrations (0.07 per cell), chromatidtype aberrations (0.05 per cell) and dicentrics (0.016 per cell)in peripheral blood lymphocytes of cancer patients significantly exceeds the average population level and similarindicators in the control group (conditionally healthy donors). It has been proven for the first time that the natureof the dose dependence of the aberration yield during irradiation in the range of low doses (0.1-0.5 Gy) is influenced by the individual radiosensitivity of cancer patients, determined by the chromosomal G2 test, with an increasein which the boundaries of the plateau (doseindependent area) on the doseeffect curve change.

CONCLUSION

Determination of individual radiosensitivity of cancer patients before the start of radiation therapyallows to reasonably identify individuals with a high risk of secondary tumors of radiation genesis, which is important for personalized planning of therapeutic radiation schemes.