{"This patient is predicted to be a CYP2D6 poor metabolizer and may be at an increased risk of a poor tamoxifen response due to low endoxifen (active component of tamoxifen) concentrations. Recommend alternative hormonal therapy such as an aromatase inhibitor for postmenopausal women or aromatase inhibitor along with ovarian function suppression in premenopausal women. Note, higher dose tamoxifen (40 mg/day) increases but does not normalize endoxifen concentrations in CYP2D6 poor metabolizers. Please consult a clinical pharmacist for more information."}