The recurrence of anemia in four or more cycles of FAC chemotherapy was connected to the presence of the rare allele G of variant p.Pro329Ala in ALDH3A1 gene (rs2228100) and common homozygote CC of another ABC transporter gene polymorphism – ABCB1 p.Ile1145= (rs1045642) (Supplementary Table 1). This evidence concerns the gene ABCG2 and anemia (phenotype).