They observed a 32% risk reduction (OR 0.68; 95% CI 0.52–0.91; p = 0.008) in breast cancer for breastfeeding for at least one year among BRCA1 germline variant carriers and a more significant decrease in risk for two or more years of breastfeeding (OR 0.51; 95% CI 0.35–0.74). This evidence concerns the gene BRCA1 and breast cancer.