Methylenetetrahydrofolate reductase gene C677T polymorphism and breast cancer risk: Evidence for genetic susceptibility

There are several evidences supporting the role of 5-10 methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms in breast cancer (BC). Case control association studies on breast cancer have been repeatedly performed over the last two decades, but results are inconsistent. We performed a meta-analysis to confirm the association between MTHFR C677T polymorphism and BC risk. The articles were retrieved by searching the PubMed, Google Scholar, and Springer Link databases. Crude odds ratios (OR) with 95% confidence intervals (CIs) was used to assess the strength of association between C677T polymorphism and BC. Publication bias was assessed by Egger's and Begg-Mazumdar tests. Meta-analysis was performed with Open Meta Analyst. Total 75 studies with 31,315 cases and 35, 608 controls were found suitable for the inclusion in the present meta-analysis. The results of meta-analysis suggested that there were moderate significant association between C677T polymorphism and BC risk using overall comparisons in five genetic models (T vs. C: OR = 1.08, 95% CI = 1.03-1.13, p = < 0.001; TT + CT vs. CC: OR = 1.06, 95% CI = 1.02-1.09, p = < 0.001; TT vs. CC: OR = 1.17, 95% CI = 1.06-1.28, p = 0.001; CT vs. CC OR = 1.05, 95% CI = 1.01-1.08, p = 0.005; TT vs. CT + CC: OR = 1.12, 95% CI = 1.03-1.22, p = 0.005). In conclusion, results of present meta-analysis showed modest association between MTHFR C677T polymorphism with breast cancer in total studies. However, sub-group analysis results based on ethnicity showed strong significant association between TT genotype and breast cancer (TT vs. CC; OR°=°1.26; 95% CI: 1.06-1.51; p = 0.009) in Asian population but in Caucasian population such association was not observed (TT vs. CC; OR°=°1.08; 95% CI: 0.99-1.14; p = 0.05).