Analysis of the sub-population of young breast cancer patients without family history and without BRCA1/2 mutation revealed that this subgroup is the most radiosensitive for all the different assays (G2 assay: 50%; HDR MN assay: 75%; LDR MN assay: 78%) (Table 2, Figures 2,3). The gene discussed is BRCA1; the disease is breast carcinoma.