Before receiving AC therapy, venous blood was collected from female patients with BC for DNA extraction and the genotyping of four SNPs: rs2228100 in ALDH3A1 gene, rs12248560 in CYP2C19 gene, rs1045642 in ABCB1 gene, and rs6907567 in SLC22A16 gene. This evidence concerns the gene CYP2C19 and breast cancer.