ABSTRACT
Forty female patients with breast cancer and 40 healthy female controls matched as regard age and socio-economic status were studied for spontaneolis and mutagen-induced sister chromatid exchange [SCEs] frequencies in their peripheral blood lymphocytes. All were non smokers, had normal children, no specific medication, x-ray exposure or recent viral infection. History of contraceptive pills was considered. Spontaneous Mean SD of SCEs/cell was 10.57 1.5 for breast cancer patients, compared to 6.22 1.9 among controls, difference proved to be statistically highly significant [p < 0.0001]. Mitomycin C [MMC] was used as a mutagen at a concentration of 0.015 ug/ml. No significant difference was observed in rates of SCEs in cultures with [MMC] between breast cancer patients and controls. However, significant difference was observed in rate of SCEs in control cultures with [MMC] between contraceptive pills users and non-users, [p < 0.01]. We conclude that metabolic stress evoked by the tumor or some clastogenic secretion of malignant cells was responsible for increased SCEs frequency in lymphocytes of breast cancer patients. Moreover, malignancy had no effect on MMC-induced SCEs rates