CHROMOSOME ABERRATIONS OUTCOME IN CANCER PATIENTS AT THE BEGINNING OF RADIOTHERAPY COURSE ON ROCUS-AM AND LINEAR ACCELERATOR CLINAC 600C

Maznyk N.O., Sypko T.S., Starenkiy V.P., Sukhina O.M., Krugova I.M.

• SI «S.P. Grigoriev Institute of Medical Radiology, NAMS of Ukraine», Kharkiv, Ukraine

Aim: the detection of chromosome aberrations level at the beginning of radiation therapy in cancer patients with different tumor localizations (uterine body cancer (UBC), lung cancer (LC) and head and neck cancer (HNC)) depending on the source of irradiation. Object and methods: 45 patients with UBC (21), LC (16) and HNC (8) were examined. Cytogenetic analysis was carried out before the start of treatment and 24 hours after receiving the first fraction of gamma-­therapy ⁶⁰Co on ROKUS-AM or megavolt therapy on the linear accelerator Clinac 600C. Results: an increase of chromosomal aberrations frequency in oncogynecological patients and LC patients already after the first fraction of external gamma- and megavolt radiation therapy was shown. There was no significant difference in cytogenetic damages outcome between the radiation sour­ces used in radiation treatment. However the increase of dicentrics level in oncogynecological patients was two times higher in comparison with that of in LC patients and was equal to 9-fold and 4.5-fold, respectively, in relation to before treatment values. Regardless to the radiation source, the excess acentric fragments le­vel with the radiotherapy start increased 1.8-fold in both patient groups. The intensity of the radiation-induced lesions formation depended on the tumor localization. The statistically significant enhance was found for total frequency and particular kinds of chromosome aberration in oncogynecological patients comparing with LC patients and HNC patients. The ratio of unstable chromosome type aberrations in oncogynecological, LC and HNC patients was 1 : 0.67 : 0.57. The distribution of the chromosome type aberrations among cells after first fraction of radiation treatment was found to be over-dispersed according to Poisson statistic in all studied groups. Conclusion: analysis of cytogenetic damages revealed the increase of chromosome aberrations yield already after first radiotherapy fraction both on ROCUS-AM and Clinac 600C, and the difference in lesions accumulation in patients depending on tumor localization. In patients with the largest volume of irradiated body fraction, namely oncogynecological patients, the highest level of chromosome type aberrations was observed in comparison with LC and HNC patients. The data obtained are of importance for correct estimation of radiation treatment effects in non-tumor cells.