The frequencies of CYP2D6 alleles and their impact on clinical outcomes of adjuvant tamoxifen therapy in Syrian breast cancer patients.

Background: Tamoxifen is one of the fundamental pillars of adjuvant endocrine therapy for hormone receptor-positive breast cancer; however, 30-50% of patients receiving tamoxifen experience tumor relapse. CYP2D6, encoded by an extremely polymorphic CYP2D6 gene, is the rate-limiting enzyme of tamoxifen bioactivation. This study aimed at determining the frequencies of the most clinically relevant CYP2D6 alleles and evaluating their impact on the responsiveness to tamoxifen in a cohort of Syrian breast cancer patients.

Frequencies of CYP2D6 genetic polymorphisms in Arab populations.

CYP2D6 is a key drug-metabolizing enzyme implicated in the biotransformation of approximately 25% of currently prescribed drugs. Interindividual and interethnic differences in CYP2D6 enzymatic activity, and hence variability in substrate drug efficacy and safety, are attributed to a highly polymorphic corresponding gene. This study aims at reviewing the frequencies of the most clinically relevant CYP2D6 alleles in the Arabs countries.