Quantitative assessment of the association between glutathione S-transferase M1 polymorphism and the risk of developing nasopharyngeal cancer

Glutathione S-transferases (GSTs) participate in the detoxification and elimination of electrophilic carcinogens by conjugating them to glutathione. Previous studies have reported a potential association between GSTM1 polymorphism and the risk of developing nasopharyngeal cancer (NPC). However, those findings remain controversial. In the present study, a meta-analysis was conducted by pooling the odds ratios (ORs) with the corresponding 95% confidence intervals (CIs) of all the available case-control studies on NPC. A comprehensive search of PubMed, Embase, Web of Science and China National Knowledge Infrastructure databases up to May 13th, 2014 was performed to identify eligible studies. A total of 12 separate publications, involving 1,593 cases of NPC and 2,868 controls, were included in the meta-analysis. The results demonstrated that the null genotype of GSTM1 was significantly associated with increased risk of developing NPC (OR=1.530, 95% CI=1.348-1.737, P-heterogeneity = 0.370). Subgroup analysis by ethnicity suggested that Asian carriers of the GSTM1 null genotype were more susceptible to NPC than individuals from other ethnic groups (OR=1.516, 95% CI=1.328-1.731, P-heterogeneity = 0.270). Sensitivity analysis confirmed the stability of these observations. In conclusion, the results from the present meta-analysis indicated that the GSTM1 polymorphism may be involved in the development of NPC, particularly in Asians.