Three-Color FISH Method: Translocations in Peripheral Blood Lymphocytes Cultures before and after Local Gamma Radiation for Breast Cancer

Purpose: Study of chromosomal aberration yields with a three-color FISH method in the peripheral blood lymphocyte cultures of patients with breast cancer before and after local irradiation. Material and methods: Venous blood was obtained from 24 patients aged from 33 to 79 years which suffering from cancer of the left or right breast after the implementation of a sectoral or radical resection of an affected organ with subsequent local adjuvant distant radiation therapy (DRT) to the scar area. Also it could be preceded by adjuvant polychimotherapy (PCT). A linear accelerator of the Trilogy system based on the Clinac iX platform was used for local irradiation. SOD was installed at 50 Gy per 25 fractions (daily 2 Gy). venous blood sampling produced to PCT and/or DRT and after 1 and/or 3 months after irradiation. A set of DNA probes to 1, 4 and 12 pairs of chromosomes was used for three-color FISH staining. Results: Levels of translocations, dicentrics and acentrics (per 100 cells) in peripheral blood lymphocyte cultures of patients up to DRT did not differ significantly with and without PCT and were amounted to average 0.63 ± 0.10; 0.10 ± 0.04 and 0.17 ± 0.06, respectively. The frequency of these chromosome rearrangements significantly increased after radiation therapy by an average of up to 4.62 ± 0.46; 1.48 ± 0.19 and 0.95 ± 0.14. The differences between 1 and 3 months of taking material after irradiation were absent. One of the patients, unlike the rest, was cytogenetically examined 11 years after a similar local irradiation, and the frequencies of translocations and dicentrics in her lymphocyte culture were 4.56 and 0.19 (per 100 cells), respectively, while they were varied from 1.63 to 10.00 for translocations and from 0.27 (0 in one patient) to 4.06 for dicentrics for other patients. Conclusion: When using a three-color FISH method there was a significant increase in the frequencies of translocations, dicentrics and acentrics in peripheral blood lymphocyte cultures of patients after DRT of breast cancer. At the same time there were more translocations than dicentrics and, apparently, they remain at the initial level for a long time. The frequency of translocations per 1 cell with translocations in the peripheral blood lymphocyte cultures in most cases exceeds 1 after local DRT of the breast cancer. The correlation between average physical doses to the whole body and cytogenetical estimates in individual patients was statistically insignificant.