How does the CYP2D6 variant affect tamoxifen metabolism?

Updated: Dec 07, 2018
  • Author: Maurie Markman, MD, MS; Chief Editor: Keith K Vaux, MD  more...
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A retrospective study conducted by Goetz et al showed that patients with the CYP2D6*4/*4 genotype had significantly shorter relapse-free time (RFT) and disease-free survival (DFS) time than did patients with *4/wt and wt/wt variants, although no difference was seen in overall survival. [6]  In addition, patients who were poor metabolizers, defined as those with *4/*4 alleles or patients on strong CYP2D6 inhibitors for 2-3 years, had significantly shorter time to recurrence, significantly worse RFT, and significantly higher risk of relapse than did patients with wt alleles and those not on CYP2D6 inhibitors. [8]

Results from a study of patients enrolled in a Stockholm Breast Cancer Group clinical trial showed that tamoxifen-treated patients with at least 1 CYP2D6*4 allele had a significantly better survival time than did those without the genetic variant. [9]

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