Impact of <i>CYP2D6</i>, <i>CYP3A5</i>, <i>CYP2C9</i> and <i>CYP2C19</i> polymorphisms on tamoxifen pharmacokinetics in Asian breast cancer patients

Abstract

The present study in Asian breast cancer patients showed that CYP2D6*5/*10 and *10/*10 genotypes are associated with significantly lower concentrations of the active metabolite of tamoxifen, endoxifen. Identifying such patients before the start of treatment may be useful in optimizing therapy with tamoxifen. The role of CYP3A5, CYP2C9 and CYP2C19 seem to be minor.