Chromosomal Radiosensitivity as an Indicator of Genetic Predisposition to Breast Cancer

An abnormally high frequency of chromatid breaks, representing unrepaired DNA double-strand breaks, in cells entering metaphase 30 to 90 min after irradiation, is a good indicator of the donor's predisposition to breast cancer. The unrepaired DNA double-strand breaks resulting from deficient repair of the radiation-induced DNA damage are evident in non cancerous cells like skin fibroblasts or blood lymphocytes from breast cancer patients carrying predisposing genes, with familial and some sporadic cancer partients and individuals at a risk to develop cancer. Such deficiency to repair DNA double-strand breaks resulting in persistent chromatid breaks, at least twofold higher than normal, after G2 phase X-irradiation may therefore be used as a marker of cancer susceptibility in cancer families.