So far individual assays for some of these polymorphisms have been established by researchers, e.g., for CYP3A (Justenhoven et al., 2010; The MARIE-GENICA Consortium on Genetic Susceptibility for Menopausal Hormone Therapy Related Breast Cancer Risk, 2010), CYP2D6 (Schaeffeler et al., 2003; Morike et al., 2008), CYP2C19 (Justenhoven et al., 2012), GST, UGT, and SULT1A (The MARIE-GENICA Consortium on Genetic Susceptibility for Menopausal Hormone Therapy Related Breast Cancer Risk, 2010) as well as companies (e.g., Applied Biosystems and Third Wave Technologies)1,.2 Here, CYP3A4 is linked to breast cancer.