Association of CYP2A6*4 with Susceptibility of Lung Cancer: A Meta-Analysis

ObjectivesTo assess the association between the variant of Cytochrome P450 2A6 whole gene deletion (CYP2A6*4) polymorphism and risk of lung cancer.MethodsTwo investigators independently searched the PubMed, Elsevier, EMBASE, Web of Science, Wiley Online Library and Chinese National Knowledge Infrastructure (CNKI). Pooled odds ratios (ORs) and 95% confidence intervals (95% CIs) for CYP2A6*4 and lung cancer were calculated in a fixed-effects model (the Mantel-Haenszel method) and a random-effects model (the DerSimonian and Laird method) when appropriate.ResultsThis meta-analysis included seven eligible studies, which included 2524 lung cancer cases and 2258 controls (cancer–free). Overall, CYP2A6*4 was associated with the risk of lung cancer (allele*4 vs. allele non-*4, pooled OR  = 0.826, 95% CI  = 0.725−0.941, P-value  = 0.004). When stratifying for population, significant association was observed in Asian (additive model, pooled OR  = 0.794, 95% CI  = 0.694−0.909, P-value  = 0.001; dominant model, pooled OR  = 0.827, 95% CI  = 0.709−0.965, P-value  = 0.016; recessive model (pooled OR  = 0.444, 95% CI  = 0.293−0.675, P-value <0.0001). In the overall analysis, a comparably significant decrease in the frequency of *4/*4 genotype was detected between cases and controls in Asian while no *4/*4 genotype was detected in Caucasian in collected data.ConclusionThis meta-analysis suggests that the CYP2A6*4 polymorphism is associated with susceptibility of lung cancer in Asian. The whole gene deletion of CYP2A6 may decrease the risk of lung cancer in Asian samples.     

A meta-analysis of the relationship between glutathione S-transferase T1 null/presence gene polymorphism and the risk of lung cancer including 31802 subjects

The relationship between glutathione S-transferase T1 (GSTT1) null/presence 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 null/presence gene polymorphism and the risk of lung cancer using meta-analysis method. The association studies were identified from PubMed, and Cochrane Library on July 1, 2012, and eligible investigations were included and synthesized using meta-analysis method. 51 reports 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 marked association between GSTT1 null genotype and lung cancer risk in overall populations (OR = 1.15, 95 % CI 1.04–1.27, P = 0.007). Furthermore, GSTT1 null genotype was associated with the lung cancer risk in Asians (OR = 1.47, 95 % CI 1.23–1.76, P < 0.0001). However, GSTT1 null genotype was not associated with the risk of lung cancer in Caucasians, Brazilian population and Africans. In conclusion, GSTT1 null genotype is associated with the lung cancer in overall populations and in Asians.     

Association between the TP53 polymorphisms and lung cancer risk: a meta-analysis

The previous published data on the association between TP53 codon 72, intron 6, and intron 3 16 bp polymorphisms and lung cancer risk remained controversial. This meta-analysis of literatures was performed to derive a more precise estimation of the relationship. 38 publications with 51 studies were selected for this meta-analysis, including 17,337 cases and 16,127 controls for TP53 codon 72 (from 43 studies), 2,201 cases and 2,399 controls for TP53 intron 6 (from four studies), and 4,322 cases and 4,558 controls for TP53 intron 3 16 bp (from four studies). When all the eligible studies were pooled into the meta-analysis of codon 72 polymorphism, there was significant association between lung cancer risk and codon 72 polymorphism in any genetic model (dominant model: OR = 1.13, 95 % CI 1.05–1.21; recessive model: OR = 1.14, 95 % CI 1.02–1.27; additive model: OR = 1.19, 95 % CI 1.05–1.33). In the subgroup analysis by ethnicity, histological type, source of control, and smoking status, significantly increased risks were observed in subgroups such as Asians, Caucasians, lung squamous cell carcinoma patients for Asians, population-based study, hospital-based study, non-smokers, and smokers. When all the eligible studies were pooled into the meta-analysis of intron 6 polymorphism, there was significant association between lung cancer risk and intron 6 polymorphism in dominant model (OR = 1.27, 95 % CI 1.11–1.44). When all the eligible studies were pooled into the meta-analysis of intron 3 16 bp polymorphism, there was significant association between lung cancer risk and intron 3 16 bp polymorphism in dominant model (OR = 1.12, 95 % CI 1.02–1.23) and additive model (OR = 1.41, 95 % CI 1.04–1.90). Additionally, when one study was deleted in the sensitive analysis, the results of TP53 intron 3 16 bp duplication polymorphism were changed in the dominant model (OR = 1.11, 95 % CI 0.87–1.42) and additive model (OR = 1.01, 95 % CI 0.65–1.56). In summary, this meta-analysis indicates that codon 72 and intron 6 polymorphisms show an increased lung cancer risk. A study with the larger sample size is needed to further evaluated gene-environment interaction on TP53 codon 72, intron 6, and intron 3 16 bp polymorphisms and lung cancer risk.     

CYP1A1 MspI polymorphism is associated with prostate cancer susceptibility: evidence from a meta-analysis

Cytochrome P450 1A1 (CYP1A1), an important phase I xenobiotic metabolizing enzyme, is responsible for metabolizing numerous carcinogens, particularly polycyclic aromatic hydrocarbons. The genetic polymorphism of CYP1A1 at the site of MspI (CYP1A1 MspI) has been implicated in prostate cancer risk, but the results of individual studies remain conflicting and inconclusive. The aim of this meta-analysis was to investigate the association of CYP1A1 MspI polymorphism with prostate cancer risk more precisely. We performed a comprehensive search of the PubMed, Embase, Web of Science, and China National Knowledge Infrastructure databases from their inception up to September 20, 2012 for relevant publications. The pooled odds ratios with the corresponding 95 % confidence intervals (95 % CIs) were calculated to assess the association of CYP1A1 MspI polymorphism with prostate cancer risk. In addition, stratified analyses by ethnicity and sensitivity analyses were conducted for further estimation. Sixteen eligible publications with 6,411 subjects were finally included into the meta-analysis after checking the retrieved papers. Overall, meta-analysis of total studies suggested that individuals carrying the TC genotype and a combined C genotype (CC + TC) were more susceptible to prostate cancer (OR_{TC vs. TT} = 1.33, 95 % CI 1.10–1.61, P _OR = 0.004; OR_{CC+TC vs. TT} = 1.27, 95 % CI 1.05–1.55, P _OR = 0.016). Stratified analysis of high quality studies also confirmed the significant association (OR_{TC vs. TT} = 1.32, 95 % CI 1.04–1.67, P _OR = 0.024; OR_{CC+TC vs. TT} = 1.30, 95 % CI 1.02–1.66, P _OR = 0.035). In subgroup analyses by ethnicity, a significant association between the CYP1A1 MspI polymorphism and risk of prostate cancer was found among Asians (OR_{TC vs. TT} = 1.44, 95 % CI 1.20–1.72, P _OR < 0.001; OR_{CC+TC vs. TT} = 1.33, 95 % CI 1.12–1.58, P _OR = 0.001), but not in Caucasians or mixed populations. The meta-analysis suggests an important role of the CYP1A1 MspI polymorphism in the risk of developing prostate cancer, especially in Asians.     

CYP1A1 *2B and *4 polymorphisms are associated with lung cancer susceptibility in Mexican patients

BACKGROUND: CYP1A1 is a gene involved in the high aryl hydrocarbon hydroxylase -inducible phenotype, which is a genetically-determined variation among individuals that has been associated with lung cancer risk. More specifically, CYP1A1 *2B and *4 polymorphisms have been associated with high susceptibility to lung cancer among cigarette smokers. MATERIALS AND METHODS: DNA was obtained from blood samples and we studied by PCR-RFLP the distribution of CYP1A1 *2B (n=248) and *4 (n=222) polymorphisms in healthy controls and 222 lung cancer patients from a Mexican population. RESULTS: Comparisons between groups showed an increased risk for lung cancer patients of *2B/*2B (18%; OR 7.6; 95% CI 3.0-19.2) and *4/ *4 genotypes (15%; OR 11.45; 95% CI 2.19-59.85) compared to the control group (1% for *2B/ *2B and 4.4% for *4/ *4). A significant association between lung cancer and homozygous *2B/ *2B passive smokers and *4/*4 ever (cigarettes) and passive smokers was also observed (p<0.05). Multivariate analysis revealed an increased risk for the *2B/*2B genotype (OR 6.83), as well as for *4/*4 (OR 28.8). CONCLUSION: The results of the study indicate a significant association between *2B/*2B and *4/*4 genotypes and the risk of developing lung cancer among Mexicans.     

A meta-analysis of the association of glutathione S-transferase P1 gene polymorphism with the susceptibility of breast cancer

Glutathione S-transferase P1 (GSTP1) is one of the important mutant sites for the cancer risk at present. The conclusions of the published reports on the relationship between GSTP1 A/G gene polymorphism and the risk of breast cancer are still debated. This meta-analysis was performed to evaluate the association between GSTP1 and the risk of breast cancer. The association reports were identified from PubMed and Cochrane Library, and eligible studies were included and synthesized using meta-analysis method. 35 investigations were included into this meta-analysis for the association of GSTP1 A/G gene polymorphism and breast cancer susceptibility, consisting of 40,347 subjects (18,665 patients with breast cancer and 21,682 controls). The association between GSTP1 A/G gene polymorphism and breast cancer risk was not found for overall population, Caucasians and Africans. Interestingly, the GSTP1 A/G gene polymorphism was associated with the susceptibility of breast cancer in Asians (G allele: OR = 1.10, 95 % CI: 1.04–1.17, P = 0.001; GG genotype: OR = 1.36, 95 % CI: 1.14–1.62, P = 0.0008; AA genotype: OR = 0.92, 95 % CI: 0.85–0.98, P = 0.02). Furthermore, the GSTP1 A/G gene polymorphism was associated with the susceptibility of breast cancer for the analysis of the controls from hospital. In conclusion, GSTP1 A/G gene polymorphism is associated with the breast cancer susceptibility in Asians. However, more studies on the relationship between GSTP1 A/G gene polymorphism and the risk of breast cancer should be performed in further.     

Ethnic differences in the association of the glutathione S-transferase T1 (GSTT1) null genotype and risk of gastric carcinoma: a systematic review and meta-analysis

We performed a systematic review and meta-analysis of the association between the glutathione S-transferase T1 (GSTT1) deletion polymorphism and gastric cancer risk in populations from different ethnic backgrounds, based on a comprehensive literature search of the MEDLINE, EMBASE, and COCHRANE libraries. Thirty-six individual case–control studies comprising 7,689 gastric cancer cases and 12,445 controls were included in our meta-analysis. Overall, the GSTT1 null genotype appeared to increase gastric cancer risk (OR 1.17, 95 % CI 1.06–1.31, p = 0.003). While Caucasian populations showed an association between the GSTT1 deletion polymorphism and gastric cancer risk (OR 1.27, 95 % CI 1.05–1.52, p = 0.01), Asian populations did not show such an association (p = 0.11). When stratified by quality assessment scores, a significant association between the GSTT1 deletion polymorphism and gastric cancer risk was observed only in the Caucasian high quality subgroup (OR 1.27 95 % CI 1.01–1.60, p = 0.05). Null genotypes for both GSTT1 and GSTM1 deletion polymorphisms also increased gastric cancer risk (OR 1.37, 95 % CI 1.04–1.80, p = 0.03). Our study suggests that the GSTT1 null genotype is associated with a significant increase in gastric cancer risk in Caucasians, but not in Asians. Further well-designed studies are required to confirm the association between GSTT1 polymorphisms and gastric cancer risk in relation to various clinicopathological factors in different ethnic groups, especially Caucasians.     

The Cytochrome P4501A1 gene polymorphisms and idiopathic male infertility risk: A meta-analysis

Studies of the relationship between male infertility and CYP1A1 polymorphisms are inconclusive. To drive a more precise estimation, we performed a meta-analysis based on 1060cases and 1225 controls from 7 published case–control studies. PubMed and CNKI literature search were conducted to identify all eligible studies investigating such a relationship. Crude odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of association in the additive model, dominant model, recessive model, and allele-frequency genetic model. In the overall analysis, the frequency of CYP1A1*2A genotype was significantly associated with susceptibility to idiopathic male infertility. Further stratified analysis by ethnicity showed notable association between the polymorphism and the risk of idiopathic male infertility in Asians. In conclusion, these results support that the CYP1A1*2A genotype polymorphism mainly contributes to idiopathic male infertility susceptibility in Asians but not in Caucasians.     

Significant association between GSTT1 null genotype and susceptibility to pancreatic cancer

Many studies have investigated the association between glutathione S-transferase T1 (GSTT1) polymorphism and risk for pancreatic cancer, but those studies have yielded contradictory findings on the association. We performed a comprehensive search in the PubMed, EMBASE, and the Chinese National Knowledge Infrastructure databases to identify relevant studies. A meta-analysis was performed to examine the association between GSTT1 polymorphism and susceptibility to pancreatic cancer by calculating the pooled odds ratios (ORs) and corresponding 95 % confidence intervals (95 % CIs). Eight studies involving a total of 4,437 individuals were included. Overall, significantly increased pancreatic cancer risk was associated with GSTT1 null genotype when all studies were pooled into the meta-analysis (random effects OR = 1.61, 95 % CI 1.06–2.44; P = 0.025). Significantly increased risk of pancreatic cancer was also found for GSTT1 null genotype in Asians when stratified by ethnicity (fixed effects OR = 2.67, 95 % CI 1.74–4.09; P < 0.001). The findings demonstrate that GSTT1 null genotype have a modest effect on the genetic susceptibility to pancreatic cancer, and GSTT1 null genotype is associated with increased risk of pancreatic cancer.     

Association between the NBS1 Glu185Gln polymorphism and lung cancer risk: a systemic review and meta-analysis

Nijmegen Breakage Syndrome protein 1 (NBS1) is one of the most important DNA repair proteins playing important roles in maintaining the genomic stability of NDA. Previous studies regarding the association between NBS1 8360G>C (Glu185Gln) polymorphism and lung cancer reported conflicting results. To derive a more precise estimation of this association, a systemic review and meta-analysis was performed. We performed a meta-analysis using eligible case–control studies to summarize the data on the association between the NBS1 Glu185Gln polymorphism and lung cancer risk. Odds ratios (ORs) with corresponding 95 % confidence intervals (95 %CIs) were pooled to assess the association between NBS1 Glu185Gln polymorphism and lung cancer risk. Six case–control studies with a total of 2,348 lung cancer cases and 2,401 controls without canner were included into the meta-analysis. Overall, there was an association between NBS1 Glu185Gln polymorphism and lung cancer risk under the dominant comparison model (fixed-effects OR _{GluGln/GlnGln vs. GluGlu}  = 1.21, 95 % CI 1.07–1.37, P = 0.002, I ² = 8.1 %). Subgroup analysis by race suggested a significant association between NBS1 Glu185Gln polymorphism and lung cancer risk in Asians (fixed-effects OR _{GluGlnGlnGln vs. GluGlu}  = 1.22, 95 % CI 1.06–1.41, P = 0.005) but not in Caucasians (fixed-effects OR _{GluGlnGlnGln vs. GluGlu}  = 1.17, 95 % CI 0.91–1.50, P = 0.220). This meta-analysis supports that there is an association between NBS1 Glu185Gln polymorphism and lung cancer risk. More studies are needed to further verify this association.     

Association of vitamin D receptor gene polymorphism with the risk of lung cancer: a meta-analysis

Abstract

Relationship between vitamin D receptor (VDR) gene polymorphism and the risk of lung cancer from the published reports are still conflicting. This study was conducted to evaluate the relationship between VDR TaqI (rs731236), BsmI (rs1544410) and ApaI (rs7975232) gene polymorphism and the risk of lung cancer using meta-analysis method. The association studies were identified from PubMed and Cochrane Library on 1 December 2013, and eligible investigations were included and synthesized using meta-analysis method. Six reports were recruited into this meta-analysis for the association of VDR gene polymorphism with lung cancer susceptibility. In the meta-analysis for ApaI gene polymorphism, AA genotype was associated with the risk of lung cancer in Asians. In the meta-analysis for BsmI gene polymorphism, B allele, BB genotype and bb genotype were associated with lung cancer in Asians, and B allele bb genotype were associated with lung cancer risk in overall populations; furthermore, bb genotype was associated with lung cancer risk in Caucasians. In the meta-analysis for TaqI gene polymorphism, t allele and TT genotype were associated with lung cancer in overall populations and in Caucasians. In conclusion, B allele bb genotype t allele and TT genotype were associated with lung cancer risk in overall populations. AA genotype, B allele, BB genotype and bb genotype were associated with the risk of lung cancer in Asians. Furthermore, bb genotype t allele and TT genotype was associated with lung cancer risk in Caucasians. However, more studies should be conducted to confirm it.     

Significant association of glutathione S-transferase T1 null genotype with esophageal cancer risk: a meta-analysis

Recent studies on the association between glutathione S-transferase T1 (GSTT1) polymorphism and risk of esophageal cancer showed inconclusive results. To clarify this possible association, we conducted a meta-analysis of published studies. Data were collected from the following electronic databases: Pubmed, Embase, and Chinese Biomedical Database (CBM). The odds ratio (OR) and its 95 % confidence interval (95 % CI) was used to assess the strength of this association. We summarized the data on the association between GSTT1 null genotype and risk of esophageal cancer in the overall population, and performed subgroup analyses by ethnicity. Finally, a total of 24 independent studies including a total of 7,801 subjects (2,965 cases and 4,836 controls) were eligible for meta-analysis. In the overall analysis, there was no significant association between GSTT1 null genotype and esophageal cancer risk (OR = 1.15, 95 % CI 0.99–1.33, P = 0.067). However, meta-analysis of adjusted ORs showed a significant association between GSTT1 null genotype and increased risk of esophageal cancer (OR = 1.30, 95 % CI 1.08–1.56, P = 0.005). Subgroup analyses by ethnicity showed there was an obvious association between GSTT1 null genotype and increased risk of esophageal cancer in East Asians (OR = 1.24, 95 % CI 1.10–1.39, P < 0.001), but not in Caucasians (OR = 0.89, 95 % CI 0.71–1.11, P = 0.300). There was no obvious risk of publication bias in this meta-analysis (Egger’s test, P = 0.784). This meta-analysis demonstrates that GSTT1 null genotype is independently associated with increased risk of esophageal cancer, and a race-specific effect may exist in this association.     

CYP1A1 and CYP2D6 polymorphism and risk of lung cancer in a North Indian population.

This case-control study was conducted to examine the association between the CYP1A1 and CYP2D6 genotypes and lung cancer risk among North Indians. The estimated relative risk for lung cancer associated with the CYP1A1 Val/Val allele was 2.68, and was four-fold when cases with small cell lung cancer (SCLC) were considered alone. With regard to the metabolism of debrisoquine, no poor metabolizers were found amongst the subjects. The odds ratio of risk with the heterozygous extensive metabolizer (HEM) genotype was 1.5. However, in the presence of at least a single copy of the variant CYP1A1 MspI allele and the CYP2D6 HEM genotype, the risk was two-fold for squamous cell carcinoma (SQCC). When the CYP1A1 Val/Val and CYP2D6 HEM genotypes were taken together, the risk for SCLC was four-fold. Stratified analysis indicated an interaction between bidi smoking and variant CYP1A1 genotypes on the risk for SQCC and SCLC. Heavy smokers (Brinkman index>400) with Val/Val genotypes were at a very high risk of developing lung cancer (odds ratio 29.30, 95% confidence interval 2.42-355, p=0.008). Heavy smokers with CYP1A1 MspI (CYP1A1*1/2A or CYP1A1*2A/*2A) genotype had a seven-fold risk for SCLC compared with non-smokers. This study is the first to be carried out on a North Indian population, and, although small, suggests that CYP1A1 and CYP2D6 polymorphisms might have a role in determining the risk for lung cancer and should be investigated further.     

The association between MTHFR C677T polymorphism and ovarian cancer risk: a meta-analysis of 18, 628 individuals

Methylenetetrahydrofolate reductase (MTHFR) enzyme plays an important role in folate metabolism and MTHFR polymorphisms have been suggested to be associated with risk of various cancers. MTHFR C677T polymorphism is a common genetic alteration and may affect the host susceptibility to ovarian cancer. The aim of this study was to investigate the association between MTHFR C677T polymorphism and ovarian cancer risk by performing a meta-analysis. Pubmed, Embase, Web of Science and Chinese Biomedical Database (CBM) databases were searched for case–control studies investigating the association between MTHFR C677T polymorphism and ovarian cancer. Odds ratio (OR) and its 95 % confidence interval (95 % CI) was used to assess this possible association. 13 individual case–control studies from 10 publications with a total of 18, 628 subjects (5, 932 cases and 12, 696 controls) were included into this meta-analysis. Meta-analyses showed there was no association between MTHFR C677T polymorphism and ovarian cancer risk in Caucasians under all five genetic models (All P values for the pooled ORs were more than 0.05), whereas there was an obvious association between MTHFR C677T polymorphism and ovarian cancer risk in Asians under four genetic models (for T vs C, OR (95 % CI) = 1.38(1.19–1.61); for TT vs CC, OR (95 % CI) = 2.32(1.63–3.29); for TT vs TC+CC, OR (95 % CI) = 2.04(1.47–2.85); for TT+TC vs CC, OR (95 % CI) = 1.36(1.12–1.65)). Subgroup analyses suggested ethnicity was the major source of heterogeneity. This meta-analysis supports an association between MTHFR C677T polymorphism and ovarian cancer risk, and there might be a race-specific effect in this association. Further studies with large sample size and careful design are needed to identify this association more comprehensively.     

CYP1A1 MspI polymorphisms and lung cancer risk: an updated meta-analysis involving 20,209 subjects

Published data describing the association between CYP1A1 MspI gene polymorphism and lung cancer risk are inconclusive. To determine a more conclusive relationship, we performed an updated meta-analysis of all eligible studies and conducted the subgroup analysis by stratification according to the ethnicity source, histological types of lung cancer, gender and smoking status of case and control populations. A total of 51 studies comprising 20,209 subjects were included in the analysis. A significantly elevated lung cancer risk was associated with two variant genotypes (for TT vs CC: OR=1.24, 95% CI=1.11-1.40; for CT and TT combined vs CC: OR=1.19, 95% CI=1.12-1.27) in the overall population. In the stratified analysis, significantly higher risks associated with lung cancer were found in Asians, Caucasians, lung SCC, lung AC and the male population. In contrast, negligible risks were found in the mixed population, lung SCLC and the female population. Additionally, a significant association was found in the smoker population, whereas no association was found in non-smoker populations. This meta-analysis suggests that the MspI polymorphisms of CYP1A1 correlate with increased lung cancer susceptibility, and that there is an interaction between the CYP1A1 polymorphism and smoking. However, the associations vary in different ethnic populations, histological types of lung cancer and the gender of case and control populations.     

Association between the CYP1A2-164 A/C polymorphism and colorectal cancer susceptibility: a meta-analysis

To date, epidemiological studies have assessed the association between CYP1A2-164 A/C polymorphism and colorectal cancer susceptibility. However, the results of these studies remained controversial. We aimed to examine the associations by conducting a meta-analysis of case–control studies. A total of 11 studies including 5,093 cases and 5,941 controls evaluated the association between the CYP1A2-164 A/C polymorphism and colorectal cancer susceptibility. No significantly associations were found in all genetic models (CC vs. AA: OR = 1.14, 95 % CI = 0.93–1.40; AC vs. AA: OR = 1.05, 95 % CI = 0.91–1.20; dominant model: OR = 1.08, 95 % CI = 0.95–1.24; recessive model: OR = 1.10, 95 % CI = 0.95–1.28). In the subgroup analysis by ethnicity or source of controls, there were still no significant associations detected in all genetic models. This meta-analysis suggested the CYP1A2-164 A/C polymorphism was not a risk factor for increasing colorectal cancer, further large and well-designed studies are needed to confirm these conclusions.     

CCND1 G870A polymorphism interaction with cigarette smoking increases lung cancer risk: meta-analyses based on 5008 cases and 5214 controls

Evidence indicates CCND1 G870A polymorphisms as a risk factor for a number of cancers. Increasing studies have been conducted on the association of CCND1 G870A polymorphism with lung cancer risk. However, the results were controversial. The aim of the present study was to derive a more precise estimation of the relationship. Meta-analyses examining the association between CCND1 G870A polymorphism and lung cancer were performed. Subgroup analyses regarding ethnicity, smoking status, histological types and source of controls were also implemented. All eligible studies for the period up to May 2012 were identified. The overall data from ten case–control studies including 5,008 cases and 5,214 controls indicated that variant A allele may have an association with increased lung cancer risk (AA vs GG: OR = 1.21; 95 % CI = 1.08–1.36, dominant model: OR = 1.09; 95 % CI = 1.00–1.19, recessive model: OR = 1.23; 95 % CI = 1.01–1.49). In the subgroup analysis by ethnicity, A allele may elevate lung cancer risk among Asians but not Caucasians or Mixed ethnicities. In smoking status subgroup, A allele was shown to associate with increased lung cancer risk among smokers but not non-smokers. In the subgroup analysis by histological types, increased cancer risks were shown in adenocarcinoma but not squamous cell carcinoma, under the homozygote comparison and recessive models. Collectively, the results of the present study suggest that CCND1 G870A polymorphism might be a low-penetrant risk factor for lung cancer, particularly among Asians and smokers. Moreover, homozygous AA alleles might have a correlation with increased lung adenocarcinoma susceptibility.     

The association between the Lys751Gln polymorphism in the XPD gene and the risk of bladder cancer

The Lys751Gln polymorphism in the XPD gene have been suggested as a risk factor for bladder cancer, however the results were inconclusive. The aim of the current study is to assess the association by meta-analysis. A total of 15 case–control studies concerning the association between the XPD Lys751Gln polymorphism and bladder cancer risk were included in the meta-analysis. The results suggested that the Lys751Gln polymorphism was not associated with an increased risk of bladder cancer in the dominant model (OR = 1.03, 95 % CI 0.95–1.11, P = 0.53 for Lys/Gln+Gln/Gln vs. Lys/Lys) in overall analysis. In the subgroup analysis by ethnicity, no significant association was found in Caucasians or Asians. Other comparatives suggested a slight significant association between the polymorphism with the risk of bladder cancer in the recessive comparative (OR = 1.14, 95 % CI 1.02–1.29, P = 0.03). The current meta-analysis indicated that the Lys751Gln polymorphism in the XPD gene might be a risk factor for bladder cancer. In the future, more large-scale case–control studies are needed to validate our results.     

MspI and Ile462Val Polymorphisms in CYP1A1 and Overall Cancer Risk: A Meta-Analysis

Background

Cytochrome P450 1A1 (CYP1A1) is a member of the CYP1 family, which is a key enzyme in the metabolism of many endogenous substrates and exogenous carcinogens. To date, many studies have examined the association between CYP1A1 MspI and Ile462Val polymorphisms and cancer risk in various populations, but their results have been conflicting rather than consistent.

Methods

To assess this relationship more precisely, a meta-analysis based on 198 publications was performed. Odds ratios (OR) and corresponding 95% confidence intervals (CIs) were used to assess the association. The statistical heterogeneity across studies was examined with a chi-square-based Q-test.

Results

Overall, a significant elevated risk of cancer was associated with CYP1A1 MspI and Ile462Val polymorphisms for all genetic models studied. Further stratified analysis by cancer types revealed that the MspI polymorphism may increase the risk of lung cancer and cervical cancer whereas the Ile462Val polymorphism may contribute to a higher risk of lung cancer, leukemia, esophageal carcinoma, and prostate cancer. In the subgroup analysis by ethnicity, obvious associations were found in the Asian population for the MspI polymorphism while an increased risk of cancer was observed in Asians and Caucasians for the Ile462Val polymorphism.

Conclusions

The results of this meta-analysis suggest that CYP1A1 MspI and Ile462Val polymorphisms contribute to increased cancer susceptibility among Asians. Additional comprehensive system analyses are required to validate this association and other related polymorphisms.     

CYP1A1 Ile462Val Polymorphism Contributes to Lung Cancer Susceptibility among Lung Squamous Carcinoma and Smokers: A Meta-Analysis

Many studies have examined the association between the CYP1A1 Ile462Val gene polymorphisms and lung cancer risk in various populations, but their results have been inconsistent. To assess this relationship more precisely, a meta-analysis was performed. Ultimately, 43 case-control studies, comprising 19,228 subjects were included. A significantly elevated lung cancer risk was associated with 2 Ile462Val genotype variants (for Val/Val vs Ile/Ile: OR = 1.22, 95% CI = 1.08–1.40; for (Ile/Val +Val/Val) vs Ile/Ile: OR = 1.15, 95% CI = 1.07–1.23) in overall population. In the stratified analysis, a significant association was found in Asians, Caucasians and lung SCC, not lung AC and lung SCLC. Additionally, a significant association was found in smoker population and not found in non-smoker populations. This meta-analysis suggests that the Ile462Val polymorphisms of CYP1A1 correlate with increased lung cancer susceptibility in Asian and Caucasian populations and there is an interaction with smoking status, but these associations vary in different histological types of lung caner.