CYP2C19 and breast carcinoma: Other investigations have not observed a statistically significant effect on cyclophosphamide pharmacokinetics associated with the CYP2C19*2 SNP (Xie et al, 2006; Ekhart et al, 2008).Variants of the other CYP enzymes investigated in this study had no impact on outcome or toxicity in this cohort of breast cancer patients.