No Association Between CYP2D6*10 Genotype and Survival of Node-negative Japanese Breast Cancer Patients Receiving Adjuvant Tamoxifen Treatment

Objective: The CYP2D6 enzyme plays a major role in converting tamoxifen to its active metabolites. We investigated whether there is an association between the CYP2D6*10 allele and clinical outcome in node-negative Japanese breast cancer patients. Methods: CYP2D6 genotyping was performed in 154 node-negative breast cancer patients who had received adjuvant tamoxifen treatment alone. The CYP2D6 genotypes were determined using the TaqMan Allelic Discrimination Assay. Results: Eighteen percent (28 of 154) of the patients carried the CYP2D6*10/*10 genotype, 40% the CYP2D6 wild-type (wt)/*10 genotype and 42% the CYP2D6 wt/wt genotype. There were no discernible correlations between clinicopathologic parameters and the CYP2D6*10 genotype. Next, we determined whether there was a correlation between the CYP2D6*10 genotype and survival and found that the clinical outcome for patients carrying the CYP2D6*10/*10 genotype was similar to those with other genotypes. Conclusions: Our results suggest that the CYP2D6*10 genotype is unlikely to have any clinical significance for prognosis of node-negative Japanese breast cancer patients receiving adjuvant tamoxifen alone.