Editor’s Choice

A Simulation Study to Compare the Treatment Effect of Tamoxifen by CYP2D6 Genotypes and Third-Generation Aromatase Inhibitors

Tamoxifen and aromatase inhibitors have been used as treatment and prevention of estrogen receptor positive breast cancer. Tamoxifen is a prodrug that is converted by the polymorphic enzyme CYP2D6 into its active form, endoxifen.  This month’s Editor’s Choice article examines CYP2D6 genotype and response to tamoxifen compared to the aromatase inhibitors, anastrozole and letrozole in postmenopausal women with estrogen receptor positive breast cancer.  The results suggest that in women who get intolerable adverse effects to aromatase inhibitors, if these women are found to be extensive metabolizers for CYP2D6 (as measured by genotyping non-tumor DNA), that the treatment effect of tamoxifen would be comparable to that of aromatase inhibitors.

-- Gwan Cheol Park,MS, Jin-A Jung, PhD, Kyun-Seop Bae, MD, PhD, and Hyeong-Seok Lim, MD, PhD,