GSTM1 null polymorphisms and oral cancer risk: a meta-analysis

Many studies have examined the association between the GSTM1 null gene polymorphism and oral cancer risk in various populations, but their results have been inconsistent. To assess this relationship more precisely, a meta-analysis was performed. The PubMed and Embase databases were searched for case–control studies published up to May 2013. Data were extracted and pooled odds ratio (OR) with 95 % confidence intervals (CI) were calculated. Ultimately, 39 studies, comprising of 4,704 oral cancer cases and 7,090 controls, were included. Overall, for null versus present, the pooled OR was 1.29 (95 % CI?=?1.20–1.40), and the heterogeneity was found in all studies. In the stratified analysis by ethnicity, significant risks were found among Asians (OR?=?1.39, 95 % CI?=?1.27–1.53; P?=?0.000 for heterogeneity), but not in Caucasians (OR?=?0.99, 95 % CI?=?0.83–1.18; P?=?0.677 for heterogeneity). In conclusion, this meta-analysis demonstrates that the GSTM1 null gene polymorphism may be an increased risk of oral cancer in Asians but not in Caucasians.     

GSTT1 null genotype contributes to hepatocellular carcinoma risk: a meta-analysis

Studies investigating the association between genetic polymorphism of glutathione S-transferase T1 (GSTT1) and hepatocellular carcinoma (HCC) risk have reported conflicting results. Therefore, we conducted this meta-analysis to provide more precise evidence. Databases including PubMed, Embase, SCOPUS, ISI Web of Science, and Wangfang were searched for relevant studies. Potential sources of heterogeneity were also assessed by subgroup analysis. Funnel plots and Egger's linear regression were used to test publication bias among the articles. Finally, a total of 28 studies involving 3,897 HCC patients and 6,117 controls were included in this meta-analysis. In a combined analysis, the summary odds ratio for HCC of the GSTT1 null genotype was 1.43 (95 % confidence interval (CI) 1.22–1.68, P?<?10^?5). In the subgroup analysis by ethnicity, significantly increased risks were found in East Asians for GSTT1 null polymorphism, while no significant associations were found among Caucasian, South Asian, and African populations. When stratified by a source of controls, both population- and hospital-based studies get consistent positive results. By pooling data from 10 studies (1,639 cases and 2,224 controls) that considered combinations of GSTT1 and GSTM1 genotypes, a statistically significant increased risk for HCC (odd ratio?=?1.85, 95 % CI 1.37–2.49) was detected for individuals with combined deletion mutations in both genes compared with positive genotypes. No evidence of publication bias was observed. Our result suggests that the GSTT1 null genotype contributes to an increased risk of HCC in East Asians and that interaction between unfavorable GSTs genotypes may exist.     

Glutathione S-transferase T1 null genotype and laryngeal cancer risk: a meta-analysis

Glutathione S-transferase T1 (GSTT1) polymorphic variation has been implicated as a risk factor for various cancers. However, previous studies investigating the association between GSTT1 null genotype and laryngeal cancer risk in Asians reported conflicting outcomes. In the present study, the possible association of laryngeal cancer risk with GSTT1 null genotype was explored by a meta-analysis. Relevant studies were identified through a systemic search of PubMed and Chinese National Knowledge Infrastructure databases. Six studies with a total of 1,824 individuals were included in the meta-analysis. The pooled odds ratio (OR) with 95 % confidence interval (CI) was used to assess the association. Meta-analysis of all included studies showed that there was an obvious association between GSTT1 null genotype and laryngeal cancer risk in Asians (OR?=?2.41, 95 % CI 1.27–4.57, P?=?0.007, I ²?=?86 %). After adjusting for heterogeneity, there was still an obvious association between GSTT1 null genotype and laryngeal cancer risk in Asians (OR?=?1.75, 95 % CI 1.36–2.24, P?I ²?=?0 %). The findings from the meta-analysis suggest that GSTT1 null genotype is associated with laryngeal cancer risk in Asians.     

Association between glutathione S-transferase M 1 null genotype and risk of ovarian cancer: a meta-analysis

Though previous studies investigated the association between glutathione S-transferase M 1 (GSTM1) null genotype and ovarian cancer risk, the effect of GSTM1 null genotype on ovarian cancer risk was still unclear. To comprehensively quantify the association between GSTM1 null genotype and ovarian cancer risk, we performed a meta-analysis. Eleven studies from ten publications were identified from PubMed database. The pooled odds ratio (OR) with its 95 % confidence interval (CI) was used to assess the association. Meta-analysis of the total 11 studies showed that GSTM1 null genotype was not associated with ovarian cancer risk (OR?=?1.03, 95 % CI 0.92–1.14, P?=?0.625). The cumulative meta-analyses showed a trend of no association between GSTM1 null genotype and ovarian cancer risk as information accumulated by year. There was no evidence of publication bias in the meta-analysis. Meta-analysis of the 11 available studies shows that GSTM1 null genotype is not associated with ovarian cancer risk.     

Association between glutathione S-transferase M1 null genotype and risk of gallbladder cancer: a meta-analysis

Glutathione S-transferases (GSTs) are a family of enzymes which are involved in the detoxification of potential carcinogens. Glutathione S-transferase M1 (GSTM1) null genotype can impair the enzyme activity of GSTs and is suspected to increase the susceptibility to gallbladder cancer. Previous studies investigating the association between GSTM1 null genotype and risk of gallbladder cancer reported inconsistent findings. To quantify the association between GSTM1 null genotype and risk of gallbladder cancer, we performed a meta-analysis of published studies. We searched PubMed, Embase, and Wanfang databases for all possible studies. We estimated the pooled odds ratio (OR) with its 95 % confidence interval (95 % CI) to assess the association. Meta-analysis of total included studies showed that GSTM1 null genotype was not associated with gallbladder cancer risk (OR?=?1.13, 95 % CI 0.88–1.46, P?=?0.332). Subgroup analysis by ethnicity showed that there was no association between GSTM1 null genotype and risk of gallbladder cancer in both Caucasians and Asians. However, meta-analysis of studies with adjusted estimations showed that GSTM1 null genotype was associated with increased risk of gallbladder cancer (OR?=?1.46, 95 % CI 1.02–2.09, P?=?0.038). Thus, this meta-analysis shows that GSTM1 null genotype is likely to be associated with risk of gallbladder cancer. More studies with well design and large sample size are needed to further validate the association between GSTM1 null genotype and gallbladder cancer.     

Association between glutathione S-transferase T1 null genotype and risk of myelodysplastic syndromes: a comprehensive meta-analysis

Myelodysplastic syndromes (MDS) are a heterogeneous group of clonal hematologic neoplasms, and the pathophysiology of these disorders is still unclear. Previous studies investigating the association between glutathione S-transferase Tl (GSTT1) null genotype and risk of MDS reported controversial results. We performed a comprehensive meta-analysis to clarify the effect of GSTT1 null genotype on risk of MDS. The strength of the association was measured by odds ratio (OR) with 95 % confidence interval (CI). Fifteen studies were finally included, involving a total of 1,796 cases and 2,502 controls. Subgroup analysis was performed by race. Meta-analysis of all 15 studies showed that the GSTT1 null genotype was significantly associated with an increased risk of MDS (OR?=?1.47, 95 % CI 1.16–1.88, P _OR?=?0.002; I ²?=?54.4 %). Besides, an obvious association was also observed after adjusting the heterogeneity (OR?=?1.32, 95 % CI 1.13–1.54, P _OR?=?0.001; I ²?=?9.0 %). Subgroup analysis by race suggested that this association existed in both Caucasians (OR?=?1.40, 95 % CI 1.04–1.89, P _OR?=?0.027) and Asians (OR?=?1.68, 95 % CI 1.00–2.81, P _OR?=?0.049). This meta-analysis suggests the GSTT1 null genotype is significantly associated with an increased risk of MDS in both Caucasians and Asians.     

The GSTT1 null genotype contributes to increased risk of prostate cancer in Asians: a meta-analysis

Background: Many studies have investigated the association between glutathione S-transferase T 1 (GSTT1)null genotype and risk of prostate cancer, but the impact of GSTT1 null genotype in Asians is still unclear owingto inconsistencies across results. Thie present meta-analysis aimed to quantify the strength of the associationbetween GSTT1 null genotype and risk of prostate cancer. Methods: We searched the PubMed, Embase andWangfang databases for studies of associations between the GSTT1 null genotype and risk of prostate cancer inAsians and estimated summary odds ratio (OR) with their 95% confidence interval (95% CI). Results: A totalof 11 case-control studies with 3,118 subjects were included in this meta-analysis, which showed the GSTT1null genotype to be significantly associated with increased risk of prostate cancer in Asians (random-effects OR= 1.49, 95% CI 1.15-1.92, P = 0.002), also after adjustment for heterogeneity (fixed-effects OR = 1.45, 95% CI1.23-1.70, P < 0.001). No evidence of publication bias was observed. Conclusions: This meta-analysis of availabledata suggested the GSTT1 null genotype does contribute to increased risk of prostate cancer in Asians.     

Maternal alcohol consumption during pregnancy and the risk of childhood acute leukemia： a meta-analysis

Objective: The authors used a meta-analytic technique to quantify the evidence of an association between ma-ternal alcohol consumption during pregnancy and childhood acute leukemia (AL), which provided a basis for the prevention of childhood AL. Methods: Relevant literatures of maternal alcohol consumption during pregnancy were comprehensively searched and screened. Subgroup meta-analysis was conducted according to the type of leukemia. Results of research data of maternal alcohol consumption during pregnancy were tested for heterogeneity. Combined OR values and 95% CIs were statistically calculated with RevMan 4.2 software; Funnel plots were applied to conduct bias analysis for those included litera-tures. Results: Ten related literatures were included after data screening, 4593 cases in Al. group and 6157 cases in control group respectively. According to heterogeneity test result (χ2=16.26, P<0.05), the combined OR values and 95% Cl were calculated with random effects model, which were 1.02(0.92-1.14), Z=0.41, P=0.68 > 0.05, indicating that there was no significant difference between maternal alcohol consumption during pregnancy and the risk of childhood acute leukemia (AL). Subgroup analysis: for the association between maternal alcohol consumption dudng pregnancy and childhood acute lympho-blastic leukemia (ALL), the combined OR value and 95% CI were 0.92 (0.84-1.00), Z=1.92, P=0.05, indicating that there was significant difference between two groups; for the association between maternal alcohol consumption during pregnancy and childhood acute non-lymphoblastic leukemia (ANLL), the combined OR values and 95% Cl were 0.82 (0.61-1.11), Z=1.30, P=0.19>0.05, indicating that there was no significant difference between two groups. Conclusion: Maternal alcohol consumption during pregnancy is a risk factor in childhood ALL, but not in childhood ANLL.     

Epoxide hydrolase genotype and orolaryngeal cancer risk: interaction with GSTM1 genotype

The human microsomal epoxide hydrolase (EH) gene contains polymorphic alleles which are associated with altered EH activity and may be linked to increased risk for tobacco-related cancers. The objective was to examine the role of EH polymorphisms in orolaryngeal cancer risk. The prevalence of the EH codons 113 and 139 polymorphisms were examined in 81 African American and 142 Caucasian incident orolaryngeal cancer patients and 335 controls frequency-matched on age, sex, and race. In Caucasians, a significant risk increase was observed for subjects with the EH(113Tyr) variant (OR=2.1, 95% CI=1.1-4.0) and predicted high-activity EH genotypes in heavy-smokers (>or=35 pack-years; OR=3.4, 95% CI=1.2-9.6). A significant association between predicted high EH activity genotypes and orolaryngeal cancer risk was observed in Caucasian subjects with the GSTM1 null (OR=3.5, 95% CI=1.3-9.3) but not GSTM [+] (OR=0.9, 95%CI=0.4-2.1) genotype. These results suggest that EH polymorphisms play an important role in risk for orolaryngeal cancer in Caucasians.     

GSTT1 genetic polymorphism and susceptibility to childhood acute lymphoblastic leukemia: a meta-analysis

Glutathione S-transferase T1 (GSTT1) genetic polymorphism has been considered as a risk factor for developing malignant diseases including acute lymphoblastic leukemia; however, the results from previous studies are inconsistent. We performed a meta-analysis of 16 published studies to investigate the association between GSTT1 null variant and risk of acute lymphoblastic leukemia in childhood. Between-study heterogeneity was assessed using the I ² statistic method. Odds ratios (ORs) with corresponding 95 % confidence intervals (95 %CI) were pooled to assess the association. Those 16 studies were from 14 publications and included a total of 2,424 cases and 3,447 controls. Meta-analysis of a total of 16 studies showed that GSTT1 null variant was significantly associated with risk of childhood acute lymphoblastic leukemia (fixed-effect OR?=?1.22, 95 %CI 1.07–1.39, P?=?0.003, I ²?=?35 %). Subgroup analysis showed that GSTT1 null variant was significantly associated with risk of childhood acute lymphoblastic leukemia in Asians (fixed-effect OR?=?1.47, 95 %CI 1.16–1.85, P?=?0.001, I ²?=?0 %). However, there was no obvious association in both Caucasians (random-effect OR?=?1.07, 95 %CI 0.83–1.38, P?=?0.59, I ²?=?53 %) and Africans (random-effect OR?=?0.99, 95 %CI 0.31–3.10, P?=?0.98, I ²?=?72 %). Therefore, the GSTT1 null variant is significantly associated with susceptibility to childhood acute lymphoblastic leukemia in Asians.     

Association between glutathione S-transferase T1 null genotype and risk of lung cancer: a meta-analysis of 55 studies

The relationship between glutathione S-transferase T1 (GSTT1) gene polymorphism and the risk of lung cancer from the published reports are still conflicting. This study was conducted to evaluate the relationship between GSTT1 polymorphism and the risk of lung cancer. A comprehensive research was conducted through the databases, and 55 studies were recruited into this meta-analysis for the association of null genotype of GSTT1 with lung cancer susceptibility, consisting of 15,140 patients with lung cancer and 16,662 controls. There was a significant association between GSTT1 null genotype and lung cancer risk in the overall populations (OR?=?1.138, 95 % CI?=?1.032–1.255, P _{heterogeneity}?=?0.000, P?=?0.009). Furthermore, GSTT1 null genotype was associated with the lung cancer risk in Asians (OR?=?1.469, 95 % CI?=?1.228–1.757, P _{heterogeneity}?=?0.000, P?=?0.000). However, GSTT1 null genotype was not associated with the risk of lung cancer in Caucasians and Africans. In conclusion, GSTT1 null genotype is associated with the lung cancer in overall populations and in Asians.     

GSTT1 null genotype contributes to increased risk of gastric cancer in Chinese population: evidence from a meta-analysis

Previous studies suggested glutathione S-transferase T1 (GSTT1) null genotype might be a candidate genetic polymorphism with a role in the susceptibility to gastric cancer, but studies form Chinese population reported controversial findings. Thus, a meta-analysis was performed to clarify the effect of GSTT1 null genotype on gastric cancer risk in Chinese population. Eligible studies were searched in Medline, Embase, and China National Knowledge Infrastructure databases. Between-study heterogeneity was assessed using the I ² statistic. Odds ratios (OR) with the corresponding 95 % confidence intervals (95 % CI) were pooled to assess the association. Twenty case–control studies involving a total of 3,204 gastric cancer cases and 5,462 controls were finally included in the meta-analysis. Meta-analysis of all 20 studies showed that GSTT1 null genotype was associated with an elevated risk of gastric cancer in Chinese population (OR?=?1.26, 95 % CI 1.09–1.46, P _OR?=?0.002). The cumulative meta-analysis showed a trend of a more obvious association between GSTT1 null genotype and risk of gastric cancer in Chinese population as information accumulated gradually. Sensitivity analysis by omitting individual study, in turns, did not materially alter the pooled ORs. This meta-analysis provides a strong evidence for the significant association between GSTT1 null genotype and gastric cancer risk in Chinese population, and GSTT1 null genotype contributes to increased risk of gastric cancer.     

Association between glutathione S-transferase T1 null genotype and glioma susceptibility: a meta-analysis

The relationship between genetic polymorphisms of glutathione S-transferase (GST) and the development of glioma has been investigated in several epidemiologic studies. However, these studies report inconsistent results. In order to get this precise result, a meta-analysis was conducted by calculating the pooled odds ratios (OR) and the 95 % confidence intervals (95 % CI). Eleven case–control research studies with a total of 2,416 glioma cases and 4,850 controls were included into this meta-analysis. The combined results based on all studies showed that there was no significant association between the GSTT1 null allele and glioma risk (OR?=?1.188, 95 % CI?=?0.929–1.520, P _{heterogeneity}?=?0.003, P?=?0.170). In the subgroup analysis, the same results were found in our work. There was no risk of publication bias in this meta-analysis. Our results suggest that GSTT1 null genotype was not associated with the increased risk of glioma.     

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.     

DNA repair gene XRCC1 polymorphisms and susceptibility to childhood acute lymphoblastic leukemia: a meta-analysis

Objective

To estimate the relationship between genetic polymorphisms of X-ray repair cross-complementing group 1 (XRCC1) and the susceptibility to childhood acute lymphoblastic leukemia (ALL).

Methods

Relevant case-control studies were enrolled in the meta-analysis. We applied Rev Man 4.2 software to pool raw data and test studies’ heterogeneity and to calculate the incorporated odds ratio (OR) and 95% confidence interval (95% CI).

Results

Our data showed that the OR for the Gln allele of the Arg399Gln polymorphism, compared with the Arg allele, was 1.35 (95% CI, 1.16-1.57; P<0.0001) for childhood ALL patients. Similarly, the homozygous genotype Gln/Gln and heterozygous genotype Arg/Gln both significantly increased the risk of childhood ALL compared with the wild genotype Arg/Arg (OR =1.58; 95% CI, 1.13-2.21; P=0.008; OR =1.51; 95% CI, 1.21-1.87; P=0.0002). The dominant model of Arg399Gln was associated with childhood ALL risk (OR =1.54; 95% CI, 1.25-1.89; P<0.0001). The ethnic subgroup analysis demonstrated that the Gln allele in all five ethnic groups was prone to be a risk factor for childhood ALL just with different degrees of correlation while Arg194Trp SNP showed a protective or risk factor or irrelevant thing in different races.

Conclusions

XRCC1 399 polymorphism may increase the risk of childhood ALL. Different ethnic groups with some gene polymorphism have different disease risks.Key Words: X-ray repair cross-complementing group 1 (XRCC1), gene polymorphism, childhood, acute lymphoblastic leukemia (ALL)     

GSTM1 polymorphism and lung cancer risk among East Asian populations: a meta-analysis

GSTM1 gene encodes a key enzyme involved in the metabolism of xenobiotics, and its polymorphisms have been related to individual susceptibility to several malignancies. Many molecular epidemiological studies were performed to investigate the association between the GSTM1 null polymorphism and lung cancer susceptibility in East Asia. However, the results were inconsistent. In order to derive a more precise estimation, we conducted this meta-analysis involving 5,909 lung cancer cases and 7,067 controls from 35 studies. We used crude odds ratios (ORs) with 95 % confidence intervals (CIs) to assess the association between GSTM1 null genotype and the risk of lung cancer. Our study found that the GSTM1 null genotype appeared to be a significant risk factor for lung cancer in East Asia population (OR?=?1.30, 95 % CI?=?1.17–1.45, P _{heterogeneity}?<?0.0001, and I ²?=?54.0 %).     

GSTT1 null genotype increases risk of premenopausal breast cancer

The NAT2, GSTM1 and GSTT1 genes are known candidate cancer susceptibility markers and have been investigated in breast cancer susceptibility with conflicting results. We conducted a case-control study to investigate the role of NAT2, GSTM1 and GSTT1 in premenopausal breast cancer. Women with the GSTT1 null genotype were found to have a significant 3.15-fold increased risk of breast cancer (95% CI = 1.7-5.8), while GSTM1 and NAT2 genotypes were not associated with breast cancer risk. Our results suggest that the GSTT1 null genotype may play a role in early onset breast cancer.     

CYP1A1 and GSTM1 polymorphisms and lung cancer risk in Chinese populations: a meta-analysis

Genetic polymorphisms of cytochrome p450 (CYP1A1) and glutathione S-transferase M1 (GSTM1) genes are thought to have significant effects on the metabolism of environmental carcinogens and thus on cancer risk, but the reported results are not always consistent. In this meta-analysis, we assessed reported studies of associations between polymorphisms of these two genes and risk of lung cancer in Chinese populations. Through a systematic literature search for publications between 1989 and 2006, we summarized the data from 46 studies on polymorphisms of MspI and exon7-Val of CYP1A1 and GSTM1 and lung cancer risk in Chinese populations, and found that compared with the wild-type homozygous genotype (type A), lung cancer risk for the combined variant genotypes (types B and C) was 1.34-fold (95% confidence interval [CI]=1.08-1.67) (Z=2.64, P=0.008); the risk for the combined variant genotypes (Ile/Val and Val/Val) of CYP1A1 exon7 was 1.61-fold (95% CI=1.24-2.08) (Z=3.62, P<0.001), compared with the Ile/Ile genotype; and that the risk for the GSTM1 null genotype was 1.54-fold (95% CI=1.31-1.80) (Z=5.32, P<0.001), compared with the GSTM1 present genotype. Therefore, in 46 published studies in Chinese populations, we found evidence of an association between the CYP1A1 variant and GSTM1 null genotypes and increased risk of lung cancer.     

Breast-feeding and risk of childhood acute leukemia.

BACKGROUND: Breast-feeding is well known to have a protective effect against infection in infants. Although the long-term effects of breast-feeding on childhood cancer have not been studied extensively, a protective effect against childhood Hodgkin's disease and lymphoma has been suggested previously from small investigations. In this study, we tested the hypothesis that breast-feeding decreases the risk of childhood acute leukemia. METHODS: A total of 1744 children with acute lymphoblastic leukemia (ALL) and 1879 matched control subjects, aged 1-14 years, and 456 children with acute myeloid leukemia (AML) and 539 matched control subjects, aged 1-17 years, were included in the analysis. Information regarding breast-feeding was obtained through telephone interviews with mothers. All leukemias combined, histologic type of leukemia (ALL versus AML), immunophenotype of ALL (early pre-B cell, pre-B cell, or T cell), and morphology of AML were assessed separately in the data analysis. RESULTS: Ever having breast-fed was found to be associated with a 21% reduction in risk of childhood acute leukemias (odds ratio [OR] for all types combined = 0.79; 95% confidence interval [CI] = 0.70-0.91). A reduction in risk was seen separately for AML (OR = 0.77; 95% CI = 0.57-1.03) and ALL (OR = 0.80; 95% CI = 0.69-0.93). The inverse associations were stronger with longer duration of breast-feeding for total ALL and AML; for M0, M1, and M2 morphologic subtypes of AML; and for early pre-B-cell ALL. CONCLUSION: In this study, breast-feeding was associated with a reduced risk of childhood acute leukemia. If confirmed in additional epidemiologic studies, our findings suggest that future epidemiologic and experimental efforts should be directed at investigating the anti-infective and/or immune-stimulatory or immune-modulating effects of breast-feeding on leukemogenesis in children.     

Glutathione s-transferase polymorphisms (GSTM1, GSTP1 and GSTT1) and the risk of acute leukaemia: a systematic review and meta-analysis

Glutathione s-transferase (GST) polymorphisms (GSTM1, GSTP1 and GSTT1) have been considered as risk factors for developing acute leukaemia in a number of studies; however the overall results of such studies are inconsistent. To investigate a putative association of GST polymorphisms with the risk of acute leukaemia, we performed a systematic review and meta-analysis of 30 published case-control studies. To take into account the possibility of heterogeneity across the studies, a statistical test was performed. The pooled odds ratios (ORs) were assessed using both a fixed-effects and a random-effects model. The pooled OR of acute leukaemia risks associated with GSTM1 null genotype, GSTP1 Val105 allele and GSTT1 null genotype were 1.22 (95% confidence interval (CI) 1.07-1.38), 1.07 (95% CI 1.00-1.13) and 1.19 (95% CI 1.00-1.41), respectively. Significantly increased risk of acute lymphoblastic leukaemia associated with GSTM1 and GSTT1 null genotypes was observed. Their pooled ORs were 1.24 (95% CI 1.17-1.31) and 1.30 (95% CI 1.06-1.60), respectively. We also found substantial evidence of heterogeneity between the studies. Our results suggest that GSTM1 and GSTT1, but not GSTP1 polymorphisms, appear to be associated with a modest increase in the risk of acute lymphoblastic leukaemia. It is conceivable that GSTM1 and GSTT1 null genotypes may thus play a role in leukemogenesis. A review of the 30 case-control studies indicates that greater attention should be paid to the design of future studies.