In another study, cancer risk reductions were in the order of 32 and 49 % among women with BRCA1 mutation who breastfed for at least one year (OR 0.68; 95 % CI 0.52–0.91; p = 0.008) and for two or more years (OR 0.51; 95 % CI 0.35–0.74; p = 0.0003), respectively. This evidence concerns the gene BRCA1 and cancer.