Association between ABCB1 G2677T/A Polymorphism and Breast Cancer Risk: A Meta-Analysis.

Several studies have investigated the relationship between ABCB1 G2677T/A polymorphism and breast cancer susceptibility; however, the published results remain controversial. Thus, we conducted a meta-analysis to synthetically evaluate the association of this polymorphism with breast cancer risk. A computerized literature search was systematically carried out in PubMed, EMBASE, ScienceDirect, China National Knowledge Infrastructure and Wanfang Databases to identify the published case-control studies investigating the relationship between ABCB1 G2677T/A polymorphism and breast cancer risk. The strength of association was assessed using odds ratios (ORs) with 95% confidence intervals (CIs). In total, six studies, including 4,791 cases and 7,042 controls, were included. The results of our quantitative synthesis suggest that there is no significant association between ABCB1 G2677T/A polymorphism and breast cancer risk in overall comparisons under four genetic models (heterozygote: OR = 1.01, 95% CI = 0.92-1.09, P = 0.90; homozygote: OR = 1.01, 95% CI = 0.65-1.55, P = 0.97; recessive model: OR = 1.06, 95% CI = 0.75-1.50, P = 0.76; and dominant model: OR = 0.98, 95% CI = 0.77-1.24, P = 0.85). Similarly, no significant association was observed in the stratification analyses by ethnicity and control source. In conclusion, this meta-analysis suggests that ABCB1 G2677T/A polymorphism is not associated with genetic susceptibility to breast cancer.