BRCA mutations: For women with BRCA1 (n=685) mutations, breastfeeding for more than one year was associated with a 22-50% reduced risk of breast cancer compared to those women who never breastfed (OR=0.55, 95% CI=0.38 to 0.80; P=0.001) [27]. This evidence concerns the gene BRCA1 and breast carcinoma.