BRCA1 and breast cancer: Of 189 BRCA1/2MUT+ women with unilateral breast cancer, 8 contralateral breast cancer cases were found (mean observation period: 3.0 years; incidence rate: 1.4%/year), compared with 4 cases of contralateral breast cancer among 892 BRCA1/2MUT− women (mean observation period: 2.2 years; incidence rate: 0.2%/year; Table 5).