Association BetweenCYP2D6Genotypes and the Clinical Outcomes of Adjuvant Tamoxifen for Breast Cancer: A Meta-Analysis

AIM: Tamoxifen is one of the most commonly used endocrine therapeutic agents for breast cancer. Although many studies have examined whether the treatment outcomes of tamoxifen for breast cancer differ according to CYP2D6 genotype, the study results have been inconsistent, and the role of CYP2D6 in the prediction of patient outcomes from tamoxifen therapy remains controversial. This study evaluated the association between CYP2D6 genotypes and postoperative tamoxifen treatment outcome in patients with breast cancer, using the available previous study results. MATERIALS & METHODS: We performed a meta-analysis of ten previous clinical reports (n = 5183) to evaluate the association between CYP2D6 genotype and hazard ratios for the recurrence risk of breast cancer after postoperative tamoxifen treatment. Pooled estimates of hazard ratios were computed using R and NONMEM® software. RESULTS: A significantly increased risk of breast cancer recurrence in patients carrying variant CYP2D6 genotypes was found in this investigation. The mean hazard ratios and 95% CI were 1.60 (1.04-2.47) in the random effect model implemented in R and 1.63 (1.01-2.62) in the random effect model in NONMEM. The bootstrap result (2000 replicates) of NONMEM was 1.64 (1.07-2.79). CONCLUSION: Our present findings suggest that genetic polymorphisms of CYP2D6 may be important predictors of the clinical outcomes of adjuvant tamoxifen treatment for the patients with breast cancer. A large-scale, prospective, randomized, well-controlled trial is warranted to confirm our findings.