Promoter hypermethylation of MGMT gene may contribute to the pathogenesis of gastric cancer: A PRISMA-compliant meta-analysis

BECKGROUND: The association of MGMT (O(6)-methyguanine deoxyribonucleic acid methyltransferase) promoter hypermethylation with gastric cancer (GC) risk has been studied extensively, but the results remained unclear. Here, we performed a meta-analysis to evaluate whether promoter hypermethylation of the MGMT gene contributed to gastric pathogenesis. METHODS: Relevant studies were identified by retrieving the PubMed, Web of Science, Embase, and China National Knowledge Infrastructure (CNKI) databases. The Newcastle–Ottawa Scale was applied to assess methodological quality of the included studies. Pooled odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated to evaluate the association of MGMT promoter hypermethylation with gastric pathogenesis. Moreover, STATA 12.0 software was used to summarize the extracted data in this meta-analysis. RESULTS: Seventeen studies, comprising 1736 cases and 1291 controls, were included in this meta-analysis. The frequency of MGMT promoter hypermethylation in the GC group (32.97%) was significantly higher than those in the control group (18.00%) (OR = 2.83, CI = 1.93–4.15, P < .05). When stratified by cancer subtype, the results indicated that the frequency of MGMT promoter hypermethylation was significantly higher in gastric adenocarcinoma than in control group (OR = 3.47, CI = 1.06–11.35, P < .05). In addition, MGMT promoter hypermethylation significantly promoted distant metastasis and lymph node (LN) metastasis of gastric tumor (for distant metastasis, OR = 4.22, CI = 2.42–7.37, P < .05; for LN metastasis, OR = 1.56, CI = 1.14–2.13, P < .05). A significant association between MGMT promoter hypermethylation and TNM-stage was also found in the present meta-analysis (OR = 2.70, CI = 1.79–4.08, P < .05). CONCLUSION: The results of this meta-analysis suggested that MGMT gene-promoter hypermethylation was significantly associated with an increased risk of GC, especially in Asians. Furthermore, MGMT gene-promoter hypermethylation might be correlated with the distant metastasis and LN metastasis of GC.