An updated pooled analysis of glutathione S-transferase genotype polymorphisms and risk of adult gliomas

Objective: Glutathione S-transferases (GSTs) are multifunctional enzymes that play a crucial role in thedetoxification of both the endogenous products of oxidative stress and exogenous carcinogens. Recent studiesinvestigating the association between genetic polymorphisms in GSTs and the risk of adult brain tumors havereported conflicting results. The rationale of this pooled analysis was to determine whether the presence of aGST variant increases adult glioma susceptibility by combining data from multiple studies. Methods: In ourmeta-analysis, 12 studies were identified by a search of the MEDLINE, HIGHWIRE, SCIENCEDIRECT andEMBASE databases. Of those 12, 11 evaluated GSTM1, nine evaluated GSTT1 and seven evaluated GSTP1Ile105Val. Between-study heterogeneity was assessed using χ2-based Q statistic and the I2 statistic. Crude oddsratios (ORs) with corresponding 95% confidence intervals (CIs) were used to estimate the association betweenGSTM1, GSTT1 and GSTP1 polymorphisms and the risk of adult gliomas. Results: The quantitative synthesisshowed no significant evidence to indicate an association exists between the presence of a GSTM1, GSTT1 orGSTP1 Ile105Val haplotype polymorphism and the risk of adult gliomas (OR, 1.008, 1.246, 1.061 respectively;95% CI, 0.901-1.129, 0.963-1.611, 0.653-1.724 respectively). Conclusions: Overall, this study did not suggestany strong relationship between GST variants or related enzyme polymorphisms and an increased risk of adultgliomas. Some caveats include absence of specific raw information on ethnic groups or smoking history onglioma cases in published articles; therefore, well-designed studies with a clear stratified analysis on potentialconfounding factors are needed to confirm these results.