O-6-methylguanine-DNA methyltransferase gene promoter methylation and lung cancer risk: A meta-analysis.

Abstract

To evaluate O-6-methylguanine-DNA methyltransferase (MGMT) gene promoter methylation pattern in tumor tissue and autologous controls (plasma, normal lung tissue, and bronchial lavage fluid [BLF]) in patients with nonsmall cell lung cancer (NSCLC). We electronic searched the MEDLINE and CNKI databases to find the open published studies related to MGMT gene promoter hypermethylation in NSCLC patients. The odds ratio (OR) for hypermethylation in plasma, BLF, and tissue was pooled by fixed or random effect model according to the statistical heterogeneity across the included studies. After searching the related databases, we finally included 13 studies in this meta-analysis. The hypermethylation rate of tumor tissue, plasma, BLF, and control tissue of MGMT gene in NSCLC patients were 0.34 ± 0.20, 0.18 ± 0.14, and 0.39 ± 0.23; the statistical heterogeneity across the studies was evaluated by Chi-square and I2-test. Moreover, no statistical heterogeneity was existed in the aspects of hypermethylation for plasma, BLF, and tissue (P < 0.05). Meta-analysis showed the hypermethylation rate in tumor tissue was significantly higher than normal lung tissue (OR = 4.18, 95% CI: 2.76-6.32) and plasma (OR = 2.37, 95% CI: 1.49-3.75) in NSCLC patients. However, for BLF (OR = 2.05, 95% CI: 0.88-4.78), the hypermethylation rate was not statistical different (P > 0.05). Hypermethylation rate in MGMT gene promoter of cancer tissue was statistical higher than autologous controls which indicated that MGMT may play an important in the cancer development.