Chromosomal Translocations in Patient’s Lymphocytes in the Long Term after Accidental Local Irradiation

Objective: to compare the frequencies of translocations detected by one-color and three-color FISH painting in the long term (24 years) after local over-irradiation (more than 100 Gy) of a patient during radiation therapy for breast cancer. Material and methods: The material for the cytogenetical study were the cultures of venous blood lymphocytes of this patient. Cultivation of lymphocytes and preparation of chromosome preparations were carried out using variants of standard methods. Chromosomes were stained separately with one-color or three-color DNA probes for 1, 4 and 12 pairs. In both cases, 1000 metaphases were analyzed. Results: In the present study, when using the one-color FISH-method, the frequency of detected reciprocal translocations was 0.5 per 100 analyzed cells, while with tricolor painting they were 2.2 times higher (1.0 per 100 metaphases). When using the available linear-quadratic dose dependence, the average dose to the whole body was estimated at 0.28 Gy, which is a consequence of the local nature of radiation damage, the death of lymphocytes in the zone of high-dose radiation damage and the obvious impossibility of their division. Conclusion: The study of the frequency of chromosomal translocations in the long term after local overexposure during therapy in a patient for breast cancer using a three-color FISH-analysis is a more sensitive method in comparison with a one-color variant of FISH-painting.