Retrospective assessment of the severity of late radiation injuries in cancer patients by cytogenetic examination

This paper presents the results of the study of long-term effect of radiation therapy on patients with different types of cancer. The aim of the retrospective study was to evaluate effect of external beam radiation therapy (EBRT) for improving rehabilitation effectiveness. To estimate the effect a cytogenetic analysis of chromosomal aberrations in peripheral blood lymphocytes was performed. The group included patients for whom clarification, confirmation or refutation of the total focal dose (TFD) indicated in the epicrisis after EBRT was required. A group of 25 patients (5 males and 20 females) was examined. The patients had different types of cancer: Hodgkin’s lymphoma, cancer of breast and prostate glands, cervical and uterine cancers, bone cancer and multisite cancer. All examined patients underwent rehabilitation in the department of surgical and conservative treatment of radiation Injuries of A. Tsyb MRRC. For examination patient’s blood lymphocytes were stained followed by fluorescence or light microscopy to image first mitosis cells. To detect aberrations chromosome preparations with stained chromosomes 2, 4, and 12 were subjected to FISH analysis. Chromosomal aberration analysis was also used for dose assessment in accordance with IAEA recommendations. As a result, it was shown that the individual response of patients varies significantly under irradiation schemes comparable in terms of total dose and fractionation. A significant role is played by the factor of the time interval between the end of EBRT and the cytogenetic analysis (∆T). There was a clear excess of the observed frequency of aberrations in the first decade after EBRT compared with the subsequent time. The work did not reveal any dependence between the total frequency of aberrations, as well as its components, on the type of cancer disease. According to the preliminary conclusion, there is a basis for applying obtained estimates of the dose coefficient for retrospective biodosimetry of patients with the diseases listed in the group. The revealed patterns of chromosomal damage induction in blood lymphocytes of cancer patients prove the need for a personalized approach to planning and implementing a radical course of therapy in order to increase its effectiveness and prevent side effects.