The only study involving CYP2C8 (alleles *3 and *4) or CYP2C9 (alleles *2 and *3) was the work by Jernström et al. (2009), who described an increased risk of early breast cancer-related deaths associated with the haplotype CYP2C8*1/*3/CYP2C9*1/*2 (Table 1). This evidence concerns the gene CYP2C8 and breast cancer.