Abstract
Background and ObjectivesStudies investigating the association between glutathione S-transferase M1 (GSTM1) 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 GSTM1 gene polymorphism with laryngeal cancer risk.MethodsThe 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 GSTM1 polymorphism with laryngeal cancer susceptibility.ResultsSeventeen studies were included in the present meta-analysis (2,180 cases and 2,868 controls). The combined results based on all studies showed that GSTM1 null genotype was associated with increased laryngeal cancer risk (OR = 1.17, 95% CI = 1.04∼1.31). When stratifying for race, GSTM1 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).ConclusionsThis meta-analysis supported that the GSTM1 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.
Highlights
Squamous cell carcinoma (SCC) of larynx is the most frequent malignancy in the head and neck region, the risk of which results from complex interactions between many genetic and environmental factors [1]
Despite many individuals have been exposed to these exogenous risk factors, laryngeal SCC does not develop in all exposed people, which is suggested that susceptibility to cancer might be due to genetic polymorphisms in certain genes that cause differences in the metabolism of carcinogens [3]
In the subgroup analysis based on source of controls, significant associations were observed in the population-based studies (OR = 1.15, 95% confidence interval (CI) = 1.01,1.31) yet not in the hospital-based studies (OR = 1.25, 95% CI = 0.93,1.67)
Summary
Squamous cell carcinoma (SCC) of larynx is the most frequent malignancy in the head and neck region, the risk of which results from complex interactions between many genetic and environmental factors [1]. Despite many individuals have been exposed to these exogenous risk factors, laryngeal SCC does not develop in all exposed people, which is suggested that susceptibility to cancer might be due to genetic polymorphisms in certain genes that cause differences in the metabolism of carcinogens [3]. Among GSTs gene family, GSTM1 gene located on the chromosome 1p13.3, participates in the deactivation of carcinogenic intermediates of polycyclic aromatic hydrocarbons present in tobacco [6], which has been found polymorphic in the population, that is, ‘‘present’’ or ‘‘null’’ genotype may characterize an individual. Studies investigating the association between glutathione S-transferase M1 (GSTM1) 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 GSTM1 gene polymorphism with laryngeal cancer risk
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