Association of TGF-β1 -509C/T polymorphisms with breast cancer risk: evidence from an updated meta-analysis.

Epidemiological studies have evaluated the association between transforming growth factor-β1 (TGF-β1) -509C/T polymorphisms and breast cancer risk. However, the results remain conflicting rather than conclusive. The aim of this study was to comprehensively clarify the association between TGF-β1 -509C/T polymorphisms and breast cancer risk. All relevant studies were searched in the electronic databases. The potential sources of heterogeneity were detected with the chi-square-based Q test. The strength of associations between TGF-β1 -509C/T polymorphisms and breast cancer risk was measured by odds ratio (OR) and 95 % confidence intervals (CI). Publication bias was tested by Begg's test and Egger's test. A total of 10 studies including 10,913 cases and 14,187 controls were included in the meta-analysis. Overall, there was no evidence of significant association of TGF-β1 -509C/T polymorphisms with breast cancer risk (TT vs. CC [OR = 0.97, 95 % CI = 0.83-1.14]; CT vs. CC [OR = 1.05, 95 % CI = 0.90-1.22]; TT + CT vs. CC [OR = 0.99, 95 % CI = 0.91-1.08]; T allele vs. C allele [OR = 0.99, 95 % CI = 0.93-1.06]). Similar results were also found in the subgroup analyses by ethnicity and source of control. When stratified by estrogen receptor (ER) status, TT genotype and T allele were associated with a decreased ER-positive breast cancer risk (OR = 0.66, 95 % CI = 0.49-0.90 and OR = 0.85, 95 % CI = 0.75-0.96, respectively). The present meta-analysis results suggest that TGF-β1 -509C/T variants may not contribute to the risk of breast cancer overall. However, T allele may be a potential protective factor for developing ER-positive breast cancer. Well-designed studies with larger sample size were required to verify our findings further.