Clinical and Prognostic Significance of O 6 -Methylguanine-DNA Methyltransferase Promoter Methylation in Patients with Melanoma: A Systematic Meta-Analysis.

Tumor suppressor gene O6 -methylguanine-DNA methyltransferase ( MGMT ) promoter methylation has been reported in melanoma. However, the clinical and prognostic significance of MGMT promoter methylation in patients with melanoma remained to be determined. A systematic search was performed to identify eligible papers published. The overall odds ratios (ORs) or hazard ratios and their 95% confidence intervals were calculated. Final 12 eligible publications involving Caucasian population were performed in this study, including 1,071 metastatic melanoma patients, 154 primary melanoma patients, and 211 normal controls. MGMT promoter methylation was significantly higher in primary or metastatic melanoma than in normal controls ( p <0.05). No difference of MGMT promoter methylation was found in primary and metastatic melanoma ( p =0.432). When metastatic melanoma was compared to normal controls, subgroup analysis showed the correlation between MGMT promoter methylation and different sample materials (tissue: OR=7.01, p <0.001 and blood: OR=12.04, p =0.005). MGMT promoter methylation was not associated with response to drug therapy and the prognosis in overall survival and progression-free survival for multivariate analysis. Our results show that MGMT promoter methylation may be correlated with the increased risk of primary or metastatic melanoma. Based on blood samples, MGMT promoter methylation may become a noninvasive biomarker for the detection of metastatic melanoma. Further additional clinical studies are necessary.