Meta-analysis of glutathione S-transferase M1 genotype and risk toward head and neck cancer.

BACKGROUND: We sought to evaluate the estimated risk of GSTM1 null genotype and squamous cell carcinoma of the head and neck (SCCHN). METHODS: The studies done so far for GSTM1 null genotype as a risk factor associated with head and neck cancer are not conclusive and have shown conflicting results. A meta-analysis has been carried out on 22 case-control studies collected from the literature. Precision of the risk estimate and presence of publication bias in those studies are also evaluated by funnel plot analysis. RESULTS: A total of 3527 cases and 4211 controls constitute the subjects of meta-analysis. The principal outcome measured was the odds ratio (OR) for the risk of head and neck cancer. Pooling the studies together, the OR was 1.50 (95% confidence interval [CI], 1.21-1.87). When stratified according to Asians and Caucasians, the OR increased in the Asians (OR, 1.93; 95% CI, 1.29-2.90), suggesting that the risk is more pronounced in Asians. However, a substantial amount of publication bias is also associated with studies conducted on the Asian population. CONCLUSION: A review of the 22 case-control studies for risk of SCCHN and GSTM1 null genotype indicate that greater attention should be paid to designing future studies so that a more precise risk estimate can be achieved.