Among the 73 BRCA1/2MUT+ women who underwent BCS, 3 ipsilateral breast cancer cases were found (mean observation period: 3.5 years; incidence rate: 1.2%/year), compared with only 2 cases among the 477 BRCA1/2MUT− women (mean observation period: 2.2 years; incidence rate: 0.2%/year; Table 4). This evidence concerns the gene BRCA1 and breast cancer.