Comparison of the radiation sensitivity of leukocytes from healthy individuals and breast cancer patients as measured by the alkaline comet assay

Background and Ënhanced sensitivity to the chromosome-damaging effects of ionizing radiation is a feature of many cancer-predisposing conditions. Ïn this study we compared the radiation sensitivity of breast cancer patients and healthy volunteers by measuring the levels of initial DNÂ damage in peripheral leukocytes using the comet assay (single-cell alkaline gel electrophoresis). Blood samples from 29 breast cancer patients and 31 healthy volunteers were assayed in vitro without radiation and immediately after exposure with 1 Gy gamma rays from a 60Ço source at a dose rate of 277.48 ± 11.51 cGy/min. The comets were analyzed by visual classification and the level of initial DNÂ damage was measured in controls and breast cancer patients. The levels of baseline DNÂ damage was 1.6-fold higher in breast cancer cases than in controls (p=0.03). Gamma rays induced initial DNÂ damage in leukocytes of cancer cases did not have a statistically significant difference with that of healthy ones. The results showed that age did not have a significant effect on DNÂ damage both in cancer cases and controls. Çonclusion: This study indicates that alkaline comet assay can be used as a simple cytogenetic assay for screening of a large number of individuals for radiosensitivity in order to direct the positive cases to more relevant screening for cancer susceptibility and to identify the radiosensitive patients with cancer for the correct use of the radiotherapy in oncology. Ôur results show that leukocytes from the breast cancer patients presented an initial radiosensitivity similar to that of healthy subjects, but probably due to a deficient repair mechanism higher baseline DNÂ damage was seen in breast cancer patients.