Pollution in the working place and social status: Co-factors in lung cancer carcinogenesis

Introduction

Apart from the association with tobacco consumption, other factors of importance for prevention and early diagnosis of lung cancer have received little attention. We present a case–control study focusing on professional exposure to carcinogens and social status.

Methods

A written questionnaire was completed by 551 consecutive patients with lung cancer and 494 patients with large bowel cancer. The groups were balanced regarding gender and age distribution. The questionnaire included data on place of birth, education, smoking history, diet and alcohol intake, body weight and height, occupation, housing conditions and family income. According to standard epidemiological criteria, professional exposure to carcinogens was classified as professions with exposure to confirmed lung cancer carcinogens, professions with exposure to suspected lung cancer carcinogens and other professions.

Results

As expected, there were significant differences between the two groups regarding smoking status. While there were no significant differences in educational levels, more immigrants were among patients with lung cancer (17.9% vs 11.6%, p = 0.005). On average, lung cancer patients had a lower body mass index (BMI) at 24.77, as compared to 26.14 for large bowel cancer (p = 0.000). Lung cancer patients had lower income and poorer housing conditions; the bivariate difference was significant both for income levels (p = 0.046) and type of residence (p = 0.009). The proportion of patients working in professions with exposures to known carcinogens was 33.5% for lung cancer, and 17.1% for large bowel cancer (p = 0.000). In the multivariate analysis, smoking (p = 0.000), BMI (p = 0.000) and type of occupation (p = 0.001) were significant factors.

Conclusions

While there is no doubt about smoking in lung cancer carcinogenesis, professional exposure to carcinogens and belonging to lower socio-economic strata also play an important role.     

The role of chemical,physical, or viral exposures and health factors in neurocarcinogenesis: implications for epidemiologic studies of brain tumors

This review highlights some future prospects and implications for epidemiologic research on the etiology of nervous system tumors. It reviews some points regarding physiology of the nervous system, in connection with mechanism of neurocarcinogenesis, and experimental studies in animals. The results of epidemiologic studies are summarized in the light of the biological and experimental observations. The following aspects are particularly emphasized: (i) higher susceptibility of the developing nervous system to neurocarcinogenic agents (in the fetus and after birth); (ii) possible implications of knowledge about mechanisms of neurocarcinogenesis regarding crossing of the blood-brain barrier, activation of oncogenes and inactivation of anti-oncogenes, relationship between chemical structure and neurocarcinogenic action; (iii) necessity of further investigation concerning the occurrence of nitrosoureas and their precursors in the environment, and the potential role of nitroso compounds in the development of human brain tumors; (iv) lack of information about promoting or inhibiting neurocarcinogenic effects, and co-carcinogenesis—among others, interaction between X-irradiation and exposure to neurocarcinogenic nitrosoureas; (v) need for studying the potential neurocarcinogenic risk of polyomaviruses BKV, JCV, and SV40 to humans.Authors are with the Institut National de la Santé et Recherche Médicale, Villejuif, France. Address for correspondence to Dr Cordier, INSERM U170, 16 Avenue Paul Vaillant-Couturier, 94807 Villejuif, France.     

Influence of NQO1, ALDH2, and CYP2E1 genetic polymorphisms, smoking, and alcohol drinking on the risk of lung cancer in Koreans

Objectives  We investigated the association of genetic polymorphisms of NQO1, ALDH2, CYP2E1, and the combined genotype of these genes on lung cancer risk, and also evaluated the association after stratification by cumulative smoking amounts and alcohol drinking levels. Methods  The case–control study was performed in 387 lung cancer patients and 387 age- and sex-matched cancer-free controls. Direct interview was conducted and the genotypes of NQO1, ALDH2, and CYP2E1 were investigated using PCR-RFLP or 5′-nuclease activity assay. Results  The proportion of individuals with occupational history of mining was significantly higher in cases than in controls. The risk of lung cancer was significantly lower in light-drinkers (<108 g/week) than non-drinkers. The NQO1 Pro/Ser + Ser/Ser genotype showed an increased risk for lung cancer with a marginal significance (OR = 1.35, 95% CI = 0.99–1.86) compared with NQO1 Pro/Pro genotype. In heavy-smokers, the combination of NQO1 Pro/Ser + Ser/Ser and CYP2E1 c1/c1 genotype was associated with a significantly increased risk for lung cancer (OR = 2.25, 95% CI = 1.14–4.43) compared with those of NQO1 Pro/Pro and CYP2E1 c1/c2 + c2/c2 genotype. We found a significant interaction between alcohol drinking level and the CYP2E1 genotype (P = 0.0227). Conclusions  Our result suggests that the risk of lung cancer is affected by smoking, alcohol drinking, and the genetic polymorphism of NQO1. In particular, genetic polymorphisms for NQO1, CYP2E1, and ALDH2 synergistically with cumulative smoking amounts and alcohol drinking levels interact in the carcinogenesis of lung cancer in Koreans.     

髓过氧化物酶基因多态性与肺癌遗传易感性的研究

背景与目的:髓过氧化物酶(myeloperoxidase,MPO)基因启动子区域-463bp处存在G/A多态位点,国外研究表明此位点与肺癌遗传易感性有关,但中国人MPO基因型与肺癌易感性关系尚未见报道,本研究拟对此问题作一探讨。方法:采用病例-对照分子流行病学方法,以PCR-RFLP技术检测98例原发性肺癌和112名健康对照MPO基因型,通过比较不同基因型者的比值比(oddsratio,OR)及其95%可信区间(confidenceinterval,CI)分析基因多态性与中国人肺癌易感性的关系。结果:正常人群G/G、G/A、A/A基因型频率分别为47.3%、42.9%和9.8%,肺癌病例组分别为63.3%、33.7%和3.0%,杂合子G/A在两组人群中分布无显著性差异(P>0.05),但病例组A/A基因型频率显著低于对照组(P<0.025)。携带至少一个等位基因A者患肺癌的风险是基因型为G/G者的52.0%(95%CI0.29～0.93)。在吸烟人群中,等位基因A对肺癌易感性的保护作用有显著性意义(OR=0.41,P<0.025),而在非吸烟人群,这种保护作用无显著性意义(P>0.25)。结论:本研究人群MPO基因多态与肺癌遗传易感性相关,等位基因A对吸烟人群的肺癌易感性有保护作用。     

DNA修复酶XRCC1基因多态性与晚期肺癌化疗敏感性的关系研究

目的:研究DNA修复酶XRCC1基因codon194和codon399多态性与肺癌患者对铂类药物为基础的化疗敏感性的关系。方法:收集经病理学确诊的晚期肺癌112例,所有病例化疗前抽静脉血,提取白细胞DNA,用多聚酶链反应-限制性片段长度多态性(PCR-RFLP)分析技术检测XRCC1基因型。所有患者均经铂类药物为基础的化疗方案治疗。结果:(1)在肺癌患者中,XRCC1194Are/Arg、Arg/Trp和Trp/Trp基因型者分别为48例(43·3%)、51例(45·9%)和12例(10·8%);XRCC1399Arg/Arg、Arg/Gln、Gln/Gln基因型者分别为65例(58·0%)、36例(32·1%)和11例(9·8%)。经化疗后,51例患者有效,总有效率45·5%。(2)XRCC1194Trp/Trp基因型者的有效率为75·0%,显著高于Arg/Arg基因型者(37·5%,χ2=5·36,P=0·0206))。前者的化疗敏感性是后者的5倍(95%CI:1·03~27·21)。同时拥有XRCC1194Trp/Trp和XRCC1399Arg/Arg基因型者的有效率为80·0%,显著高于其他基因型者(P=0·0417,OR=5·40,95%CI:0·98~38·90)。结论:XRCC1基因多态性与晚期肺癌对铂类药物为基础的化疗敏感性相关,检测XRCC1基因型可以预测晚期肺癌化疗的敏感性。     

A population-based study of glutathione S-transferase M1, T1 and P1 genotypes and risk for lung cancer

A deletion polymorphism for glutathione S-transferase M1 (GSTM1) has been related to risk for lung cancer among smokers in some studies but not in others. We examined GSTM1, a GSTT1 deletion polymorphism and a common GSTP1 gene variant (iso→val), as risk factors for lung cancer in a population-based case-control study of men. Cases (N=274) were males identified from 1993 to 1996 through the Fred Hutchinson Cancer Research Center Cancer Surveillance System registry for western Washington State. Male age-matched controls (N=501) were selected by random-digit dialing. Subjects participated in a telephone interview and blood draw. GSTM1 and GSTT1 were genotyped with a multiplex PCR assay using beta-globin as a positive control, and GSTP1 single nucleotide variant determined with PCR-based oligonucleotide ligation assays. GSTM1 absence was associated with a modest elevation in risk among all cases (odds RATIO=1.27, 95% CI 0.91–1.77) and among non-small cell cancers (adenocarcinoma OR=1.58, 95% CI 0.99–2.52; squamous cell OR=1.40, 95% CI 0.83–2.34). Risk associated with GSTM1 null was increased two to sixfold among heavy smokers. GSTT1 was not associated with lung cancer risk and GSTP1 val was non-significantly associated with a modest reduction in risk, particularly among heavy smokers. No specific combination of GST genotypes was particularly associated with risk. These results support previous reports that the GSTM1 null genotype is associated with a modest increase in risk for lung cancer, particularly among heavy smokers, suggest no role for GSTT1 and the need for further study of GSTP1.     

Meta-Analysis of the Association between the rs8034191 Polymorphism in AGPHD1 and Lung Cancer Risk

Background: Possible associations between the single nucleotide polymorphism (SNP) rs8034191 in theaminoglycosidephosphotransferase domain containing 1 (AGPHD1) gene and lung cancer risk have been studiedby many researchers but the results have been contradictory. Materials and Methods: A computerized searchfor publications on rs8034191 and lung cancer risk was performed. Odds ratios (ORs) with 95% confidenceintervals (CIs) were calculated to assess the association between rs8034191 and lung cancer risk with 13 selectedcase-control studies. Sensitivity analysis, test of heterogeneity, cumulative meta-analysis, and assessment ofbias were also performed. Results: A significant association between rs8034191 and lung cancer susceptibilitywas found using the dominant genetic model (OR=1.344, 95% CI: 1.285-1.406), the additive genetic model(OR=1.613, 95% CI: 1.503-1.730), and the recessive genetic model (OR=1.408, 95% CI: 1.319-1.503). Moreover,an increased lung cancer risk was found with all genetic models after stratification of ethnicity. Conclusions: Theassociation between rs8034191 and lung cancer risk was significant using multiple genetic models, suggestingthat rs8034191 is a risk factor for lung cancer. Further functional studies of this polymorphism and lung cancerrisk are warranted.     

TP53 Arg72Pro and XPD Lys751Gln Gene Polymorphisms and Risk of Lung Cancer in Bangladeshi Patients

Background: Tumor suppressor gene (TP53) is considered as the most frequently mutated gene in almost all forms of human cancer. Moreover, genetic variations in the XPD gene affect the DNA repair capacity increasing cancer susceptibility. Polymorphisms within these genes can play a major role in determining individual lung cancer susceptibility. However, several studies have investigated this possibility; but reported conflicting results. Therefore, the objective of this study was to investigate the role of TP53 Arg72Pro and XPD Lys751Gln gene polymorphisms on lung cancer susceptibility in the Bangladeshi population. Materials and Methods: Study subjects comprised of 180 lung cancer patients and 200 healthy volunteers. Genetic polymorphism of TP53 was determined by multiplex PCR-based method, while XPD genotypes were analyzed using Polymerase Chain Reaction-based Restriction Fragment Length Polymorphism (PCR-RFLP) method. Lung cancer risk was estimated as odds ratio (OR) and 95% confidence interval (CI). Results: From the results, no significant association between TP53 Arg72Pro polymorphism and lung cancer risk was observed. Whereas, patients with homozygous mutant variants (Gln/Gln) of XPD at codon 751 were found significantly associated with lung cancer risk when compared to the control (OR=3.58; 95% CI=1.58-8.09; p=0.002). Lung cancer risk was found significantly higher with Gln/Gln variants of XPD among smokers (OR=4.03; 95% CI=1.11-14.63; p=0.026). Significant increased risk of lung cancer was found with Arg/Pro genotypes of TP53, Lys/Gln and Gln/Gln variants of XPD in individuals with family history of cancer (OR=3.44; 95% CI=1.36-8.72; p=0.011; OR=3.17; 95% CI=1.20-8.39; p=0.024; OR=16.35; 95% CI=0.92-289.5; p=0.007, respectively). Conclusion: The findings indicated that homozygous mutant variants (Gln/Gln) of XPD were associated with increased lung cancer risk, whereas TP53 Arg72Pro polymorphism was not associated with risk of lung cancer among Bangladeshi patients.     

Effect of XPD and TP53 Gene Polymorphisms on the Risk of Platinum-Based Chemotherapy Induced Toxicity in Bangladeshi Lung Cancer Patients

Background: Platinum-based drugs, including cisplatin and carboplatin, are the most active and extensively used agents for treating lung cancer. Genetic polymorphisms of DNA repair gene XPD and tumor suppressor gene TP53 are connected with alterations in enzyme activity. They may help explain interindividual differences in toxicity outcomes after platinum-based chemotherapy for lung cancer. Therefore, this study aimed to investigate XPD Lys751Gln and TP53 Arg72Pro polymorphisms on the risk of platinum-based chemotherapy-induced toxicity in lung cancer patients in the Bangladeshi population. Patients and Methods: Study subjects comprised of 180 platinum-based chemotherapy treated histologically confirmed lung cancer patients. Genetic polymorphisms of XPD were ascertained by Polymerase Chain Reaction-based Restriction Fragment Length Polymorphism (PCR-RFLP), while TP53 genotypes were analyzed using the multiplex PCR-based method. Toxicity was assessed based on the Common Terminology Criteria for Adverse Events (CTCAE v5.0). Results:From the results, there was no significant association observed between grade 1-2 or grade 3-4 platinum-based chemotherapy induced toxicities like anemia and XPD codon 751 (Lys/Gln: OR=1.40, 95% CI=0.75-2.64, p>0.05; Gln/Gln: OR=1.07, 95% CI=0.45-2.52, p>0.05 and Lys/Gln+Gln/Gln: OR=1.31, 95% CI=0.73-2.38, p>0.05) or TP53 codon 72 genetic polymorphisms (Arg/Pro: OR=0.64, 95% CI=0.34-1.17, p>0.05; Pro/Pro: OR=0.46, 95% CI=0.15-1.42, p>0.05 and Arg/Pro+Pro/Pro: OR=0.62, 95% CI=0.34-1.15, p>0.05). Similar results were found between neutropenia, leukopenia, thrombocytopenia and gastrointestinal toxicities and XPD Lys751Gln or TP53 Arg72Pro genetic polymorphisms. Conclusion: These findings indicated that no significant association was found between either XPD codon 751 or TP53 codon 72 genetic polymorphisms and platinum-based chemotherapy-related toxicities in Bangladeshi lung cancer patients.     

Polymorphism in GSTM1, GSTT1, and GSTP1 and Susceptibility to Lung Cancer in a Japanese Population

Polymorphisms in glutathione S-transferases (GSTs) may predispose to lung cancer through deficient detoxification ‍of carcinogenic or toxic constituents in cigarette smoke, although previous results have been conflicting. Three GST ‍polymorphisms (GSTM1, GSTT1 and GSTP1) were determined among 86 male patients with lung carcinomas and ‍88 healthy male subjects. We found no significant increase in the risk of lung cancer for any genotypes for the nulled ‍GSTM1 [odds ratio (OR)=2.0; 95% confidence interval (95% CI)= 0.8-5.3], the nulled GSTT1 (OR=2.0; 95% CI=0.8- ‍5.1) or the mutated (the presence of a Val-105 allele) GSTP1 (OR=0.96; 95% CI=0.4-5.5). The GST polymorphisms ‍alone may thus not be associated with susceptibility to lung carcinogenesis in male Japanese. However, individuals ‍with a concurrent lack of GSTM1 and GSTT1 had a significantly increased risk (OR=2.7; 95% CI=1.0-7.4) when ‍compared with those having at least one of these genes. No other combinations were associated with lung cancer ‍risk. These results suggest that there may be carcinogenic intermediates in cigarette smoke that are substrates for ‍both GSTM1 and GSTT1 enzymes and that lung cancer risk is increased for individuals who are doubly deleted at ‍GSTM1 and GSTT1 gene loci. Additional large studies are needed to confirm this observation.     

hOGG1, p53 genes, and smoking interactions are associated with the development of lung cancer

This study aimed to investigate the effects of Ser/Cys polymorphism in hOGG1 gene, Arg/Pro polymorphism in p53 gene, smoking and their interactions on the development of lung cancer. Ser/Cys polymorphism in hOGG1 and Arg/Pro polymorphism in p53 among 124 patients with lung cancer and 128 normal people were detected using PCR-RFLP. At the same time, smoking status was investigated between the two groups. Logistic regression was used to estimate the effects of Ser/Cys polymorphism and Arg/Pro polymorphisms, smoking and their interactions on the development of lung cancer. ORs (95% CI) of smoking, hOGG1 Cys/Cys and p53 Pro/ Pro genotypes were 2.34 (1.41-3.88), 2.12 (1.03-4.39), and 2.12 (1.15-3.94), respectively. The interaction model of smoking and Cys/Cys was super-multiplicative or multiplicative, and the OR (95% CI) for their interaction item was 1.67 (0.36 -7.78). The interaction model of smoking and Pro/Pro was super-multiplicative with an OR (95%CI) of their interaction item of 5.03 (1.26-20.1). The interaction model of Pro/Pro and Cys/Cys was multiplicative and the OR (95%CI) of their interaction item was 0.99 (0.19-5.28). Smoking, hOGG1 Cys/Cys, p53 Pro/Pro and their interactions may be the important factors leading to the development of lung cancer.     

Lack of Assocation of Glutathione S-transferase T1 Gene Null and Susceptibility to Lung Cancer in China: a Meta-analysis

Background: Variation in metabolic genes is regarded as an important factor in processes leading to cancer.However, the effect of GSTT1 null genotype is divergent in the form of lung cancer. Methods: Studies wereconducted at different research databases from 1990 to 2013 and the total odds ratio (OR) and 95% confidenceinterval (CI) were calculated for lung cancer. Review Manager 5.2 and STATE 12 are employed. Results: TotalOR value is calculated from 17 articles with 2,118 cases and 2,915 controls. We discovered no significant increasein lung cancer risk among subjects carrying GSTT1 null genotype [OR = 1.15; 95% CI 0.97-1.36] in this metaanalysis.Conclusion: The GSTT1 deletion polymorphism does not have a significant effect on the susceptibilityto lung cancer overall in China.     

NAT2 and CYP1A2 Polymorphisms and Lung Cancer Risk in Relation to Smoking Status

We investigated the associations between lung cancer and the gene polymorphisms of the drug metabolizingenzymes, containing cytochrome P450 1A1 (CYP1A1), cytochrome P450 1A2 (CYP1A2), glutathione S-transferaseclass mu (GSTM1), and N-acetyltransferase 2 (NAT2). The study involved 113 lung cancer patients and 121 noncancercontrols divided into never, light and heavy smokers according to pack-years of smoking in Japanese byusing PCR-RFLP. For light smokers, the lung cancer risk of NAT2 intermediate-slow was significantly increased[the adjusted odds ratio (OR): 10.9, 95% confidence intervals (95%CI): 1.75-67.5, P-value: 0.010]. Moreover,never smokers having joint genotypes of NAT2 intermediate-slow and CYP1A2*1F A/A was also associated withincreased the lung cancer risk (OR: 4.95, 95% CI: 1.19-20.6, P-value: 0.028). We suggested that light smokerswith intermediate-slow NAT2 activity were at highest risk for lung cancer and the gene-gene interaction based onintermediate-slow NAT2 activity and high CYP1A2 activity would be increased a lung cancer risk among neversmokers.     

Association of CYP2E1 and NAT2 Polymorphisms with Lung Cancer Susceptibility among Mongolian and Han Populations in the Inner Mongolian Region

Purpose: To explore associations of CYP2E1 and NAT2 polymorphisms with lung cancer susceptibilityamong Mongolian and Han populations in the Inner Mongolian region. Materials and Methods: CYP2E1 andNAT2 polymorphisms were detected by PCR-RFLP in 930 lung cancer patients and 1000 controls. Results: (1)Disequilibrium of the distribution of NAT2 polymorphism was found in lung cancer patients among Han andMongolian populations (p=0.031). (2) Lung cancer risk was higher in individuals with c1, D allele of CYP2E1RsaI/PstI, DraI polymorphisms and slow acetylation of NAT2 (c1 compared with c2, OR=1.382, 95%CI: 1.178-1.587, p=0.003; D compared with C, OR=1.241, 95%CI: 1.053-1.419, P<0.001; slow acetylation compared withrapid acetylation, OR=1.359, 95%CI:1.042-1.768, p=0.056) (3) Compared with c2/c2 and rapid acetylation, c1/c1together with slow acetylation synergetically increased risk of lung cancer 2.83 fold. (4) Smokers with CYP2E1c1/c1, DD, and NAT2 slow acetylation have 2.365, 1.916, 1.841 fold lung cancer risk than others with c2/c2, CCand NAT2 rapid acetylation, respectively. (5) Han smokers with NAT2 slow acetylation have 1.974 fold lungcancer risk than others with rapid acetylation. Conclusions: Disequilibrium distribution of NAT2 polymorphismwas found in lung cancer patients among Han and Mongolian populations. Besides, Han smokers with NAT2slow acetylation may have higher lung cancer risk compared with rapid acetylation couterparts. CYP2E1 c1/c1, DD and NAT2 slow acetylation, especially combined with smoking, contributes to the development of lungcancer. CYP2E1 c1/c1 or DD genotype and NAT2 slow acetylation have strong synergistic action in increasinglung cancer risk.     

ＧＳＴＭ１基因多态性与川北地区肺癌易感性关系的研究

目的　探讨谷胱苷肽硫转移酶Ｍ１（ＧＳＴＭ１）基因多态性与川北地区汉族人群肺癌易感性的关系。方法　采用病例对照研究和聚合酶链式反应（ＰＣＲ）技术检测川北地区１２５例肺癌患者（肺癌组）和１２５例非肿瘤患者（对照组）ＧＳＴＭ１基因缺失型的频率,评价其与肺癌易感性的关系。结果　ＧＳＴＭ１缺失基因型［ＧＳＴＭ１（－）］频率在肺癌组和对照组分别为５８.４％和５６.８％,差异无统计学意义（Ｐ＝０.８２２）;ＧＳＴＭ１（－）基因型与肺鳞癌（ＯＲ＝０.９７,９５％ＣＩ：０.５２～１.８３,Ｐ＝０.９３４）和腺癌（ＯＲ＝０.９４,９５％ＣＩ：０.４２～２.０４,Ｐ＝０.８４４）风险亦无明确关系。结论　ＧＳＴＭ１各基因型与肺癌风险无明确关系。     

Association between Restriction Fragment Length Polymorphism of the Human Cytochrome P450IIE1 Gene and Susceptibility to Lung Cancer

Cytochrome P450IIE1 (P450IIE1) is involved in metabolic activation of carcinogenic nitrosamines, aniline and benzene. We detected a restriction fragment length polymorphism of the human P450IIE1 gene with the restriction endonuclease Oral. The population was thus divided into three genotypes, namely, heterozygotes (CD) and two forms of homozygotes (CC and DD). The distribution of these genotypes among lung cancer patients differed front that among controls with statistical significance of P< 0.05 (x²=7.01 with 2 degrees of freedom). This result strongly suggests that host susceptibility to lung cancer is associated with the Dral polymorphism of the P450IIE1 gene.     

Association between X-ray repair cross complementing group 1 codon 399 and 194 polymorphisms and lung cancer risk: A meta-analysis

Genetic variations in DNA repair genes are thought to modify DNA repair capacity and suggested to be related to cancer risk. However, epidemiological results have been inconsistent. In this meta-analysis, we assessed reported studies of association between polymorphisms of X-ray repair cross complementing group 1 (XRCC1) codon 399 and 194, and lung cancer risk. We found decreased lung cancer risk among subjects carrying XRCC1 codon 194 Arg/Trp genotype [odds ratio (OR) = 0.88, 95% confidence interval (95% CI): 0.79–0.97], using 4848 cases and 6592 controls from 16 studies. There was no association between lung cancer risk and XRCC1 codon 399 polymorphism in total population, when stratified by source of control, we found a protective effect of the XRCC1 codon 399 Gln/Gln and Arg/Gln or Gln/Gln polymorphisms for lung cancer on the basis of population control (OR = 0.73, 95% CI: 0.58–0.92; OR = 0.86, 95% CI: 0.77–0.97, respectively). Data indicated that certain XRCC1 codon 399 and 194 variant may affect the susceptibility of lung cancer. Recommendations for further studies include pooling of individual data to facilitate evaluation of multigenic effects and detailed analysis of effect modification by environmental exposure.     

High Susceptibility to Lung Cancer Analyzed in Terms of Combined Genotypes of P450IA1 and Mu-class Glutathione S-Transferase Genes

Lung cancer is closely associated with cigarette smoking. Aromatic hydrocarbons in smoke, including benzo[n]pyrene, first require metabolic activation by Phase I enzymes, cytochrome P450, to their ultimate forms, and these activated forms are then subjected to detoxification by Phase II enzymes, especially glutathione S-transferases. Thus, genetically determined susceptibility to lung cancer may depend on the metabolic balance between Phase I and Phase II enzymes. In this study, we identified individuals genetically at high risk of lung cancer in terms of polymorphisms of the P450IA1 gene and GST1 gene. The relative risk of individuals with a combination of the genotypes of both a homozygous rare allele of the P450IA1 gene and the nulled GST1 gene was remarkably high at 5.8 for lung cancer and 9.1 for squamous cell carcinoma compared with other combinations of genotypes.