Association between MDR1 C3435T polymorphism and risk of breast cancer.

The C3435T (rs1045642) polymorphism, located in multi-drug resistance gene 1 (MDR1), has demonstrated its role in decreasing the P-gp activity level which is related to the carcinogenesis. Many published studies have evaluated the association between the MDR1 C3435T polymorphism and breast cancer risk. However, the results remain conflicting rather than conclusive. To derive a more precise estimation of the association between MDR1 C3435T polymorphism and risk of breast cancer, we performed a meta-analysis comprised of 10 case-control studies, including 5282 breast cancer cases and 7703 controls. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to evaluate the strength of the association. The overall results indicated that the variant genotypes were associated with a significantly increased risk of breast cancer (TT versus CC: OR=1.45, 95% CI=1.14-1.30, TT versus CT/CC: OR=1.13, 95% CI=1.04-1.23, TT/CT versus CC: OR=1.22, 95% CI=1.02-1.46). Our results suggest that the MDR1 C3435T polymorphism may contribute to individual susceptibility to breast cancer.