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, Pheterogeneity=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, Pheterogeneity=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.