Baseline and therapy-induced chromosome damages in peripheral blood lymphocytes of breast cancer patients assessed by the micronucleus assay

Purpose: Radiotherapy (RT) alone or in combination with chemotherapy (CT) leads nearly always to increase of DNA damage in cancer patients. The purpose of this study was to determine the variability rate and individual sensitivity of breast cancer (BC) patients to the applied RT and RT in combination with CT. Methods: The analysed sample included 30 women with histologically confirmed BC. The frequency of micronuclei (MN) was estimated in peripheral blood lymphocytes (PBL) by using the cytokinesis-block micronucleus (CBMN) assay before the administered therapy and one month later. Results: The mean therapy-induced MN value was significantly higher (p < 0.001) compared with mean baseline MN Both therapies (RT and combined RT+CT) significantly increased the MN frequency in patients' lymphocytes(p < 0.001), but without significant differences in the therapy-induced MN frequency between these two groups (p > 0.05). The administered therapy induced significant difference in cell kinetics (p < 0.05). The results showed a wide range of inter-individual variability in both baseline and the therapy-induced MN frequency. Conclusion: The applied therapies increased the MN frequency in PBL in BC patients, and the presented data indicate absence of synergistic effect of these two therapies. None of the variation factors (age, smoking and therapy type) had influence on the noticed variability.