Glutathione S-transferase M1 null genotype is associated with increased risk of oral cancer in East Asians: a meta-analysis.

The association between glutathione S-transferase M1 (GSTM1) null genotype and risk of oral cancer in East Asians is uncertain owing to the inconclusive results from published studies. In the present study, we performed a meta-analysis of 12 studies from three East Asian countries (China, Japan, and Korea). Those 12 studies consisted of 1,718 cases and 2,236 controls. The pooled odds ratio (OR) and corresponding 95 % confidence interval (95 %CI) were calculated to assess the relationship. Overall, the meta-analysis showed that GSTM1 null genotype was associated with increased risk of oral cancer in East Asians (OR = 1.48, 95 %CI = 1.09-2.00, P = 0.011). The results of the cumulative meta-analysis further identified the significant association above. Subgroup analysis by countries showed that the association was still significant in Japan (OR = 1.56, 95 %CI = 1.10-2.22, P = 0.012), but not in China (OR = 1.35, 95 %CI = 0.68-2.68, P = 0.393) and Korea (OR = 1.35, 95 %CI = 0.79-2.32, P = 0.271). In conclusion, the meta-analysis suggests that GSTM1 null genotype is associated with increased risk of oral cancer in East Asians. Further studies are needed to provide new and comprehensive assessments on the association in China and Korea.