Glutathione S-Transferase M1 Gene Polymorphism and Laryngeal Cancer Risk: A Meta-Analysis

<div><h3>Background and Objectives</h3><p>Studies investigating the association between glutathione S-transferase M1 (<em>GSTM1</em>) gene polymorphism and laryngeal cancer risk have reported conflicting results. The aim of the present study was to conduct a meta-analysis assessing the possible associations of <em>GSTM1</em> gene polymorphism with laryngeal cancer risk.</p> <h3>Methods</h3><p>The relevant studies were identified through a search of PubMed, Embase, ISI Web of Knowledge and Chinese National Knowledge Infrastructure until May 2011 and selected on the basis of the established inclusion criteria for publications, then a meta-analysis was performed to quantitatively summarize association of <em>GSTM1</em> polymorphism with laryngeal cancer susceptibility.</p> <h3>Results</h3><p>Seventeen studies were included in the present meta-analysis (2,180 cases and 2,868 controls). The combined results based on all studies showed that <em>GSTM1</em> null genotype was associated with increased laryngeal cancer risk (OR = 1.17, 95% CI = 1.04∼1.31). When stratifying for race, <em>GSTM1</em> null genotype exhibited increased laryngeal cancer risk in Caucasians (OR = 1.15, 95% CI = 1.01∼1.31), while no significant association was detected in Asians (OR = 1.25, 95% CI = 0.80∼1.96). In the subgroup analysis based on source of controls, significant associations were observed in the population-based studies (OR = 1.15, 95% CI = 1.01∼1.31) yet not in the hospital-based studies (OR = 1.25, 95% CI = 0.93∼1.67). Furthermore, in the subgroup analysis based on sample size, significant associations were also found in studies with at least 50 cases and 50 controls (OR = 1.15, 95% CI = 1.02∼1.30) but not in studies with fewer than 50 cases or 50 controls (OR = 1.46, 95% CI = 0.87∼2.46).</p> <h3>Conclusions</h3><p>This meta-analysis supported that the <em>GSTM1</em> gene polymorphism was associated with laryngeal cancer, particularly in Caucasians, and these associations varied in different subgroup, which indicated that population-based study with larger sample size was more appropriate in design of future study.</p>