PHARMACOGENETICS OF TAMOXIFEN
(CYP2D6 GENE TEST)
Background
Tamoxifen, a molecule essentially prescribed for the treatment of breast cancer, is a pro-drug which must be activated by the enzyme CYP2D6 before becoming pharmacologically active. In post-menopausal women, CYP2D6 can become an indirect indicator of the after-effects of primary breast cancer being treated with tamoxifen.
CYP2D6 genotypes
| Class | Frequency | Genotypes (examples) | Commentary |
| Extensive metabolizer (EM) | 92% | *1*1, *1*4, *1*3 | No sign of reduced CYP2D6 activity |
| Poor metabolizer (PM) |
8% | *4*4, *4*6, *3*4 | Strongly reduced CYP2D6 activity |
The gene tests includes the most important non-functional CYP2D6 alleles (*3, *4, *6).
Indications for testing
Specimen Shipping
Literature:
Punglia RS, Burstein HJ, Winer EP, Weeks JC. Pharmacogenomic variation of CYP2D6 and the choice of optimal adjuvant endocrine therapy for postmenopausal breast cancer: a modeling analysis. J Natl Cancer Inst. 2008;100:642-8.
Goetz MP, Kamal A, Ames MM. Tamoxifen pharmacogenomics: the role of CYP2D6 as a predictor of drug response. Clin Pharmacol Ther. 2008;83:160-6.
