Association of CYP2C19 polymorphisms with survival of breast cancer patients using tamoxifen: results of a meta- analysis.

BACKGROUND Previous studies accessing the association of CYP2C19 with outcomes of patients using tamoxifen for breast cancer have yielded conflicting results. The aim of this meta-analysis is to obtain a more precise estimate of effects of CYP2C19 polymorphisms and to clarify their effects on survival of the breast cancer patients using tamoxifen. MATERIALS AND METHODS A systematic search of PubMed and Embase was performed, comparing patients with or without CYP2C19*2 and CYP2C19*17, relevant articles searched for. The following outcomes were included from the eligible studies: disease-free survival (DFS) and overall survival (OS), expressed by hazard ratios (HR) with corresponding 95% confidence interval (CI). Subgroup analysis by genotypes was also performed. Pooled estimates were calculated using random-effect model in accordance to the heterogeneity. RESULTS Six studies met the inclusion criteria. The integrated OR on the association between CYP2C19 and DFS, calculated by the random-effect model, was 0.54 (95%CI=0.34-0.84, p=0.013). Subgroup analysis showed that both CYP2C19*2 and CYP2C19*17 were associated with increased survival. The pooled results of two studies for OS were OR=0.46 (95%CI=0.21-1.01, p=0.233). CONCLUSIONS This meta-analysis suggests that the CYP2C19*2 and CYP2C19*17 genotypes are associated with increased survival in breast cancer patients using tamoxifen.