Breast cancer (BC) is the most common type of malignancy in female patients and 
radio-treatment is the conventional therapy even if a great number of studies 
reported that enhanced sensitivity to ionizing radiation as measured as 
chromosome effects is present in a significant proportion of cancer patients, 
including breast cancer ones. In this study we analysed whether peripheral blood 
lymphocytes from sporadic BC patients and healthy subjects showed a different 
sensitivity to ionizing radiation and whether cytogenetic radiosensitivity may 
serve as a breast cancer risk biomarker. To test this hypothesis, the in vitro 
radiation sensitivity was measured by using both G(0) and G(2) chromosome 
radiosensitivity assays, on 46 subjects (23 BC patients and 23 healthy 
subjects). Results show that cancer patients are more radiosensitive than 
healthy controls and that G(2) assay could be more appropriate to define the 
individual radiosensitivity if compared to G(0) assay.