E-cadherin gene promoter hypermethylation may contribute to the risk of bladder cancer among Asian populations

• The first meta-analysis of E-cadherin gene methylation and bladder cancer
• E-cadherin methylation may increase the risk of bladder cancer.
• Detection of E-cadherin methylation may be a promising biomarker for bladder cancer.
• This meta-analysis will be helpful in clarifying current controversies.

There are increasing scientific evidences suggesting that E-cadherin gene promoter hypermethylation may contribute to the development and progression of bladder cancer, but existing studies have yielded inconclusive results. This meta-analysis aims to assess the role of E-cadherin promoter hypermethylation in bladder carcinogenesis. We conducted an extensive literature search for relevant studies on PubMed, Embase, Web of Science, Cochrane Library, and CBM databases from their inception through May 1st, 2013. This meta-analysis was performed using the STATA 12.0 software. Crude risk ratio (RR) with 95% confidence interval (CI) was calculated. Ten clinical studies were included in this meta-analysis with a total of 620 bladder cancer samples, 199 normal adjacent samples and 131 normal urothelium tissue. Our meta-analysis revealed that the methylation frequencies in bladder cancer tissues were obviously higher than those in normal control tissues (RR = 2.02, 95%CI: 1.00–4.12, P = 0.050). Subgroup analysis by ethnicity indicated that higher methylation frequencies were observed in bladder cancer tissues among Asian populations (RR = 2.35, 95%CI: 1.11–4.95, P = 0.025), but not among Caucasian populations (RR = 1.62, 95%CI: 0.48–5.53, P = 0.439). Univariate and multivariate meta-regression analyses showed that ethnicity may be the major source of heterogeneity (P < 0.05). No publication bias was detected in this meta-analysis (P = 0.358). The present meta-analysis indicates that E-cadherin gene promoter hypermethylation may contribute to increased risk of bladder cancer among Asian populations.