A provider considers prescribing tamoxifen for a woman with breast cancer. Upon reviewing results of genetic testing, the prescriber notes that the patient has variations in the CYP2Dy allele resulting in a deficiency of the CYP2D6 isoenzymes. What action will this deficiency warrant in the prescribing of tamoxifen, a CYP2D6 substrate?

Question

Quizplus · Accepted Answer

Tamoxifen requires activation by the CYP2D6 enzyme to its active metabolite, endoxifen. A deficiency in CYP2D6 due to genetic variations can lead to inadequate activation of tamoxifen, rendering it less effective in treating breast cancer. Therefore, an alternative treatment may be considered.

A Provider Considers Prescribing Tamoxifen for a Woman with Breast