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. (c) 2005 Wiley Periodicals, Inc.