Análise comparativa do polimorfismo genético da glutationa transferase, do Helicobacter pylori e do vírus Epstein-Barr entre a área do tumor e as margens de ressecção proximal e distal do câncer gástrico / Comparative analysis of glutathione transferase genetic polymorphism, Helicobacter pylori and Epstein-Barr virus between the tumor area and the proximal and distal resection margins of gastric cancer

RESUMO Objetivo: comparar o polimorfismo dos genes Glutationa S-transferase teta 1 (GSTT1) e Glutationa S-transferase mu 1 (GSTM1) da área do tumor com as margens proximal e distal de espécimes de estômago ressecados de pacientes com câncer gástrico, e investigar a presença do DNA do vírus Epstein-Barr (EBV) e Helicobacter pylori. Métodos: coletamos prospectivamente amostras teciduais da área do tumor e das margens de ressecção proximal e distal dos estômagos de dez pacientes com adenocarcinoma gástrico submetidos à gastrectomia com linfadenectomia D2 e submetemos esses espécimes à extração de DNA. Comparamos a área do tumor com as margens proximal e distal dos estômagos ressecados para o polimorfismo dos genes GSTT1 e GSTM1 e investigamos a presença de DNA do EBV e H. pylori. Utilizamos o exon 5 do gene p53 como controle interno da reação de PCR multiplex. Resultados: em um paciente, detectamos genótipos GSTT1 e GSTM1 nulos na área do tumor, em contraste com a presença de ambos os genes nas margens proximal e distal. Encontramos DNA do EBV e H. pylori na área do tumor e também nas margens proximal e distal. Em outro paciente, a margem proximal foi negativa para GSTT1 e o DNA do EBV foi negativo na margem distal. Em três pacientes, o EBV-DNA foi negativo apenas na margem distal. Conclusão: este é o primeiro relato em que diferentes genótipos, infecção por EBV-DNA e H. pylori foram observados no mesmo paciente, indicando provável deleção desses genes em resposta à progressão tumoral e heterogeneidade intratumoral.

ABSTRACT Objective: to compare the polymorphism of the Glutathione S-transferase theta 1 (GSTT1) and Glutathione S-transferase mu 1 (GSTM1) genes from the tumor area with the proximal and distal margins of stomach specimens resected from patients with gastric cancer, and to investigate the presence of Epstein-Barr virus (EBV) DNA and Helicobacter pylori. Methods: we prospectively collected tissue specimens from the tumor area and from the proximal and distal resection margins of the stomachs of ten patients with gastric adenocarcinoma who underwent gastrectomy with D2 lymphadenectomy, and submitted these specimens to DNA extraction. We compared the tumor area with the proximal and distal margins of the resected stomachs for polymorphism of GSTT1 and GSTM1 genes and investigated the presence of EBV-DNA and H. pylori. We used the p53 exon 5 gene as an internal control of the multiplex PCR reaction. Results: in one patient, we detected null GSTT1 and GSTM1 genotypes in the tumor area, in contrast to the presence of both genes in the proximal and distal margins. We found EBV-DNA and H. pylori in the tumor area and also in the proximal and distal margins. In another patient, the proximal margin was negative for GSTT1, and EBV-DNA was negative in the distal margin. In three patients, EBV-DNA was negative only in the distal margin. Conclusion: this is the first report where different genotypes, EBV-DNA and H. pylori infection were observed in the same patient, indicating a probable deletion of these genes in response to tumor progression and intratumoral heterogeneity.

Human glutathione S-transferase polymorphisms associated with prostate cancer in the Brazilian population

Objective To evaluate the influence of polymorphisms in GSTA1, GSTM1, GSTT1, and GSTP1 in the risk of developing Prostate Cancer (PCa) in a population of Rio de Janeiro and compare the distribution of allele and genotype frequencies of the polymorphisms analyzed in the present study population with other regions in the country and different ethnic groups. Materials and Methods We analyzed a sample of the Brazilian population, comprising 196 patients with PCa treated by the urology services of the Brazilian National Cancer Institute (INCA) and Mario Kroeff Hospital (HMK), and 208 male blood donors from the Clementino Fraga Filho Hospital, Federal University of Rio de Janeiro (UFRJ). The polymorphisms were determined in DNA, extracted from peripheral blood leucocytes using the Polymerase Chain Reaction and Restriction Fragment Length Polymorphism (PCR-RFLP). Results Our results showed that the distribution of polymorphisms can vary significantly according to the Brazilian region and ethnic groups. The distribution of allele and genotype frequencies of the polymorphism GSTA1 was statistically different between cases and controls. Genotypes (A / B + B / B) were associated with protection (OR = 0.61, 95 % CI = 0.40-0.92) for PCa in comparison to genotype A / A. Conclusion The distribution of genotype frequencies of the polymorphism GSTA1 was statistically different between the case and control groups (p = 0.023), and the presence of genotypes A / B and B / B suggests a protective role against the risk of PCa compared to genotype A / A. This is the first study that reports the genotypic frequency of this polymorphism and its association with PCa in a Brazilian population sample. .

Nullity of GSTT1/GSTM1 related to pesticides is associated with Parkinson's disease / Nulidade de GSTT1/GSTM1 relacionada a pesticidas associa-se com doenca de Parkinson

Genetic and environmental factors affect the pathogenesis of Parkinson's disease (PD). Genetic variants of the enzyme glutathione S-transferases (GST) may be related to the disease. This study aimed to evaluate the influence of genetic variants of GST (GSTT1/GSTM1) and their association with the exposure to environmental toxins in PD patients. We studied 254 patients with PD and 169 controls. The GSTM1/GSTT1 variants were analyzed by polymerase chain reaction. We applied the Fisher's exact test and the χ2 test for statistical analysis (p<0.05). The present and absence for GSTT1 and GSTM1 were similar in patients and controls. The null for GSTT1 and GSTM1 (0/0) and exposure to pesticides prevailed in patients (18%) compared to controls (13%, p=0.014). This study suggests the association between PD and previous exposure to pesticides, whose effect may be enhanced in combination with null for GSTT1/GSTM1.

Fatores genéticos e ambientais influenciam a patogênese da doença de Parkinson (DP). Variantes genéticas das enzimas glutationa S-transferases (GST) parecem estar envolvidas com a doença. Os objetivos deste estudo foram avaliar a influência de variantes genéticas de GST (GSTT1/GSTM1) e sua associação com exposição a toxinas ambientais em pacientes com DP. Foram estudados 254 pacientes com DP e 169 controles. As variantes para GSTM1/GSTT1 foram analisadas por reação em cadeia da polimerase. Para análise estatística foram aplicados os testes de Fisher e do χ2 (p<0,05). Tanto a presença quanto a nulidade para GSTT1 e GSTM1 foram semelhantes em pacientes e controles. A nulidade para GSTT1 e GSTM1 (0/0) e contato com agrotóxicos prevaleceu nos pacientes (18%) em relação aos controles (13%, p=0,014). Este estudo sugere associação entre DP e contato prévio com agrotóxicos, cujo efeito parece potencializado em combinação com nulidade para GSTT1/GSTM1.

Frecuencia de los polimorfismos CYP1A1*2A y deleción del gen GSTM1 en pacientes con carcinoma de células escamosas de laringe en relación al hábito tabáquico: estudio piloto en Chile / Frequency of CYP1A1*2A and GSTM1 gene polymorphisms in Chilean patients with squamous cell carcinoma of the larynx in relation to smoking habit: a pilot study

Introducción: Entre los factores de riesgo para cáncer laríngeo (CL) son relevantes el consumo de tabaco y alcohol. Estos xenobióticos son metabolizados por un grupo de enzimas, entre las cuales están CYP1A1 y GSTM1, cuyas variantes polimórficas se postulan como factores de riesgo para esta enfermedad. Objetivos: Describir la frecuencia de las variantes de los polimorfismos de CYP1A1 y GSTM1 en un grupo de pacientes diagnosticados con CL. Analizar la posible correlación entre las variantes genéticas de ambas enzimas y la presencia de CL. Evaluar la influencia del hábito tabáquico en el riesgo de aparición de cáncer escamoso de laringe en pacientes con genotipos de riesgo. Material y método: Se seleccionaron 35 pacientes con CL entre los años 2000 y 2010 en Servicio de Otorrinolaringología del HBLT y 124 controles reclutados en el Centro de Investigaciones Farmacológicas y Toxicológicas (IFT). A todos los individuos se les registraron datos demográficos y extrajo una muestra de sangre para analizar las variantes polimórficas de CYP1A1 y GSTM1, mediante PCR-RFLP. Resultados: De un total de 35pacientes 54,3% presentan el genotipo GSTM1 (-/-) y 17,1% el genotipo CYP1A1*2A C/C. En el grupo control (n =140) estas frecuencias fueron de 19,35°% y 10,48%o, respectivamente. Se observó una correlación entre GSTM1 y el CL, estratificado por el hábito tabáquico y alcohólico. No se encontraron relaciones estadísticamente significativas con el hábito alcohólico y/o tabáquico. No se observaron asociaciones entre la patología y la combinación de genotipos o entre genotipos y el hábito tabáquico o alcohólico. Conclusiones: Los resultados muestran una asociación estadísticamente significativa entre la deleción de GSTM1 (-/-) y el riesgo de presentar CL, lo que refleja el importante papel que juega esta enzima en la desintoxicación de compuestos cancerígenos. Sin embargo, se requiere incrementar el número de pacientes para establecer apropiadamente la relación genético-ambiental que permite adjudicar un papel relevante a estos biomarcadores.

Introduction: Tobacco and alcohol consumption are recognized risk factors for squamous cell carcinoma of the larynx. These xenobiotics are metabolized by numerous enzymes, among which, CYP1A1 and GSTM1 gene polymorphisms have been identified as risk factors for developing tobacco related cancers as lung and laryngeal carcinomas. Nevertheless, these polymorphisms have not been studied in Chilean patients with squamous cell carcinoma of the larynx. Aim: To describe, for the first time, the frequency of CYP1A1 and GSTM1 gene polymorphisms in Chilean patients with squamous cell carcinoma of the larynx. Material and method: We conducted a case-control study. The case group consisted of 35 Chilean patients with squamous cell carcinoma of the larynx; the control group was formed by 124 Chilean subjects without cancer diagnosis. Demographic data as age, sex and quantification of tobacco smoking and alcohol consumption were recorded in all individuals. CYP1A1 and GSTM1 gene polymorphisms were evaluated by polymerase chain reaction and restriction enzymes (PCR-RFLP). Results: The frequency of CYP1A1*2A C/C genotype was 54, 3°% among laryngeal cancerpatients and 17,1%% among control subjects. The frequency ofGSTM1 (-/-) genotype was 19,35 %% among laryngeal cancer patients and 10,48%% among control subjects. There were no statistically significant relationships between this gene polymorphisms and tobacco smoking or alcohol consumption. There were no associations between the presence of both gene polymorphisms in the same individual and the presence of laryngeal cancer. Interestingly we found an OR of 8.69 (CI 2.90 to 26.01) for GSTM1 (-/-) polymorphism and laryngeal cancer, stratified by tobacco smoking and alcohol consumption. Conclusions: Our work shows that the deletion of GSTM1 could be an important risk factor for squamous cell carcinoma of the larynx in Chilean patients. This finding reflects the important role that detoxification of carcinogenic compounds plays in Chilean population. However, it is necessary to increase the number of studied patients to properly establish the genetic-environmental relationship ascribed to these biomarkers.

GSTM1, GSTT1, and GSTP1 polymorphisms, breast cancer risk factors and mammographic density in women submitted to breast cancer screening / Polimorfismos GSTM1, GSTT1 e GSTP1, fatores de risco para câncer de mama e densidade mamográfica em mulheres submetidas a rastreamento mamográfico

Genetic polymorphisms in genes related to the metabolism of xenobiotics, such as genes of the glutathione S-transferases (GSTM1, GSTT1, and GSTP1) superfamily have been associated with an increased risk for breast cancer (BC). Considering the high incidence of BC in the city of Porto Alegre in southern Brazil, the purpose of this study was to characterize genotypic and allelic frequencies of polymorphisms in GSTM1, GSTT1, and GSTP1, and correlate these molecular findings with established risk factors for breast cancer including mammographic density, in a sample of 750 asymptomatic women undergoing mammographic screening. Molecular tests were performed using the multiplex polymerase chain reaction (PCR) for GSTM1 and GSTT1, and quantitative PCR for GSTP1 polymorphisms. Overall, the frequencies of GSTM1 and GSTT1 null genotypes were 45% and 21%, respectively. For GSTP1 polymorphism, genotypic frequencies were 44% for the Ile/Ile genotype, 44% for the Ile/Val genotype, and 12% for Val/Val genotype, with an allelic frequency of 66% for the wild type allele in this population, similar to results of previous international publications. There was a statistically significant association between the combined GSTM1 and GSTT1 null genotypes (M-/T-) and mammographic density in post menopausal women (p = 0.031). When the GSTT1 null (T-) genotype was analyzed isolated, the association with mammographic density in post menopausal women and in the overall sample was also statistically significant (p = 0.023 and p = 0.027, respectively). These findings suggest an association of GSTM1 and GSTT1 null genotypes with mammographic density.

Polimorfismos genéticos em genes relacionados com o metabolismo de xenobióticos, como os genes da superfamília das glutationa S-transferases (GSTM1, GSTT1 e GSTP1) têm sido associados com o aumento do risco para câncer de mama (CM). Considerando a alta incidência de CM na cidade de Porto Alegre, região Sul do Brasil, a proposta deste estudo foi caracterizar genótipos e frequências alélicas dos polimorfismos GSTM1, GSTT1 e GSTP1, e correlacionar esses achados moleculares com fatores de risco já estabelecidos para câncer de mama, incluindo densidade mamográfica, em uma amostra de 750 mulheres assintomáticas durante o rastreamento mamográfico. Para os testes moleculares foi utilizado multiplex da reação em cadeia de polimerase (PCR) para GSTM1 e GSTT1, e PCR quantitativo para o polimorfismo GSTP1. As frequências dos genótipos GSTM1 e GSTT1 nulos foram 45% e 21%, respectivamente. Para o polimorfismo GSTP1, as frequências genotipicas foram: 44% para o genótipo Ile/Ile, 44% para o genótipo Ile/Val e 12% para o genótipo Val/Val. A frequência do alelo lle nesta população foi 66%, semelhante a outros estudos. Houve uma associação significativa entre a combinação dos genótipos (T-/M-) nulos e densidade mamográfica nas mulheres pós-menopáusicas (p = 0,031). Quando analisamos isoladamente o genótipo GSTT1 nulo (T-) também encontramos uma associação significativa com a densidade mamográfica nas mulheres pós-menopáusicas (p = 0,027) e na amostra total. Estes achados sugerem uma associação dos genótipos (T-/M-) nulos com densidade mamográfica.

Polimorfismos nos genes MMP2, MMP13, CYP1A1, GSTM1 e EMX2 e endometriose / Polymorphisms in MMP2, MMP13, CYP1A1, GSTM1 and EMX2 and endometriosis

A endometriose é uma doença que afeta de 10 a 15% das mulheres em idade fértil. Trata-se de uma doença crônica dependente de estrogênio, caracterizada pela presença de tecido endometrial fora da cavidade uterina. É uma doença multifatorial e poligênica que ainda apresenta etiologia desconhecida. Estudos moleculares relacionam a suscetibilidade à endometriose com polimorfismos genéticos específicos. Os principais genes estudados são responsáveis pelos mecanismos biológicos da doença, como por exemplo, metabolismo do estrogênio, receptores hormonais e detoxificação celular. O objetivo do presente artigo é revisar as pesquisas relacionadas aos genes CYP1A1, MMP2, MMP13, GSTM1 e EMX2, para avaliar as possíveis implicações na patogênese da endometriose

Endometriosis is a disease that affects 10 to 15% of women on reproductive age. It is an estrogen-dependent chronic disease, which is characterized by the presence of endometrial tissue outside the uterine cavity. It is a polygenic and multifactorial disease that still has unknown etiology. Molecular studies relate susceptibility to specific genetic polymorphisms with endometriosis. The main studied genes are responsible for the biological mechanisms of disease, such as estrogen metabolism, hormone receptors, and cellular detoxification. The aim of this paper is to review the research related to CYP1A1, MMP2, MMP13, GSTM1, and EMX2 genes, in order to assess the possible implications in the pathogenesis of endometriosis

Sistema Glutation-S-Transferase como fator prognóstico no carcinoma papilífero da tireoide / GST genes expression as prognostic factor in papillary thyroid cancer

OBJETIVO: Analisar se existe relação entre os fatores moleculares dos genes GTS e a mortalidade dos pacientes com câncer de tireoide dado pelo índice AMES de prognóstico clínico. MÉTODOS: Foram coletadas amostras da tireoide de 66 pacientes com carcinoma papilífero (53 mulheres e 13 homens), de modo a permitir extração do material genético das enzimas. Foram constituídos dois grupos, segundo os fatores prognósticos clínicos de alto e baixo risco, de acordo a classificação AMES. Cada grupo foi avaliado pela presença ou não do genótipo nulo para as enzimas estudadas, correlacionando-os com os fatores prognósticos clínicos (AMES). RESULTADOS: Foram analisados os resultados de 17 doentes com alto risco (grupo A) e 49 com baixo (grupo B). Todas combinações de genótipos do GSTT1 e GSTM1 foram encontrados. O genótipo nulo dos dois genes do grupo de alto risco foi encontrado em 5,8 por cento e no de baixo risco em 6,1 por cento. CONCLUSÃO: A presença ou deleção dos genes GST (GSTT1 e GSTM1) não são bom fatores prognósticos no câncer papilífero da tireoide.

PURPOSES: Analyze the relationship between the AMES classification and molecular factors from Glutation-S-Transferase System, specifically the GSTT1 and GSTM1 in patients with well differentiated thyroid cancer. METHODS: Samples of thyroid tissue of 66 patients with papillary thyroid carcinoma were obtained (53 women and 13 men). Patients were divided in two groups (high and low risk) according to the AMES classification. In each group, presence of the null genotype of both GST enzymes system was studied. These results were compared with the AMES classification. Samples were obtained in the operating room immediately after thyroidectomy, placed in cryotubes, immersed in liquid nitrogen and stored in a freezer at -80ºC. DNA of this enzymes was extracted by the fenol-cloroformium method. RESULTS: There were 17 high risk patients and 49 low risk patients. The null genotype of the high risk group was 5.8 percent and in the other group was 6.1 percent. CONCLUSION: There was no relationship between absence of genes GSTT1 and GSTM1 and prognosis of the papillary thyroid carcinoma when compared to the AMES classifications.

Características mamográficas do câncer de mama associadas aos polimorfismos GSTM1 e GSTT1 / Polymorphisms GSTM1 and GSTT1 and sporadic breast cancer mammographic features

INTRODUÇÃO: As enzimas do sistema da glutationa S-transferase (GST) modulam os efeitos da exposição a vários agentes citotóxicos e genotóxicos. Os genes GSTM1 e GSTT1 são polimórficos em humanos e suas deleções têm sido associadas ao aumento do risco de várias neoplasias, dentre elas o câncer de mama. OBJETIVO: Comparar a freqüência das deleções dos genes GSTM1 e GSTT1 em mulheres sadias e com câncer de mama e comparar as características mamográficas do câncer entre mulheres portadoras e não portadoras das referidas deleções. MÉTODOS: Foram determinadas as freqüências das referidas deleções por PCR em 100 pacientes portadoras de câncer de mama esporádico tratadas de setembro de 2004 a junho de 2005 e em 169 mulheres sadias doadoras de sangue no mesmo período e comparadas através do odds ratio (OR) com seus respectivos IC 95 por cento. Foram revistos os prontuários e as mamografias das pacientes com câncer e avaliadas características mamográficas (padrão de distribuição do parênquima fibro-glandular, achados mamográficos ao diagnóstico e classificação BI-RADS), correlacionando-as às deleções gênicas através do cálculo da RP (razão de prevalência) com seus respectivos IC 95 por cento. RESULTADOS: O GSTM1 esteve deletado em 40 por cento dos cânceres e em 44,4 por cento dos controles (OR=1,20; IC 95 por cento 0,70-2,04; p=0,5659) enquanto o GSTT1 em 20 por cento e 19,5 por cento, respectivamente (OR=0,73; IC 0,37-1,44; p=0,4124). O padrão mamográfico denso esteve associado à deleção homozigótica do GSTM1 (RP= 2,43; IC 1,11-4,08). Não se observou associação entre as deleções do sistema GST e achados mamográficos ao diagnóstico e classificação BI-RADS. CONCLUSÃO: A deleção homozigótica do gene GSTM1 associou-se ao padrão mamográfico denso.

INTRODUCTION: Enzymes of the Glutathione S-transferase system (GST) modulate the effects of exposure to several cytotoxic and genotoxic agents. The GSTM1 and GSTT1 genes are polymorphic in humans and their deletions have been associated to increased risk of many cancers, including breast cancer. OBJECTIVE: To evaluate the occurrence of homozygous deletions of the GSTM1 and GSTT1 genes in women with sporadic breast cancer and in women without cancer and to compare breast cancer mammographic features between patients with and without these deletions. METHODS: The study evaluated 100 patients with sporadic breast cancer treated from September 2004 to June 2005 and 169 women without cancer, determining the frequency of the above-mentioned deletions by PCR and calculating the odds ratios and their 95 percent confidence intervals. Medical files and mammograms of 100 patients with breast cancer were evaluated and correlated with mammographic features such as density, mammographic findings and the BI-RADS classification. These findings were correlated with the genetic deletions by the PR (Prevalence-Ratio) with their respective 95 percent confidence intervals. RESULTS: The GSTM1 gene was deleted in 40 percent of the cancers and in 44.4 percent of controls (OR = 1.20; CI 95 percent 0.70 - 2.04; p=0.5659) while the GSTT1 gene was deleted in 20 percent and 19.5 percent, respectively (OR = 0.73; CI 95 percent 0.37-1.44; p=0.4124). High mammographic density had been associated with GSTM1 deletion (PR 2.43; CI 1.11 to 4.08). GST deletions were not associated with predominant mammographic findings and the BI-RADS classification. CONCLUSION: GSTM1 homozygous deletion was associated with high mammographic density.

Variantes alélicas de CYP1A1 y GSTM1 como biomarcadores de susceptibilidad a cáncer gástrico: influencia de los hábitos tabáquico y alcohólico / Cytochrome P4501A1 (CYP1A1), glutathione S transferase M1 (GSTM1) polymorphisms and their association with smoking and alcohol consumption as gastric cancer susceptibility biomarkers

Background: Gastric cancer (GaC) is the second cause of death by cancer in the world and one of the first causes in Chile. However, the burden of this disease shows remarkable worldwide variation probably explained by environmental and genetic factors. The role of susceptibility low penetrance genes and environmental and dietary factors in the etiology of gastric cancer is not well-known. Aim: To analyze the possible association between CaG susceptibility, genetic (CYP1A1 and GSTM1 polymorphisms) and environmental (tobacco and alcohol) factors. Patients and Methods: In a case-control study, we included 73 patients with a pathologically diagnosed GaC and 263 controls. DNA was extracted from peripheral blood to detect allele variants for CYP1A1 and GSTM1, using polymerase chain reactions and digestion with restriction enzymes. Results: There was a clear association of smoking and alcohol ingestion with GaC with odds ratios (OR) of 2.54 (95 percent confidence intervals (CI) of 1.45-4.46 and OR of 3.36 (95 percent CI 1.76-6.41), respectively. Polymorphic variants of CYP1A1 and GSTM1 had no association with GaC. However, the m2 variant of CYP1A1 significantly modifies the risk induced by tobacco or alcohol (OR 13.65; 95 percent CI 3.15-59.05 y 8.37; 95 percent CI 1.86-37.64, respectively). Conclusions: Subjects that carry the m2 allelic variant of CYP1A1 and are exposed to tobacco smoke or alcohol have a significantly higher risk of developing gastric cancer.

Polimorfismos en los genes de desintoxicación CYP1A1, CYP2E1, GSTT1 y GSTM1 en la susceptibilidad al cáncer gástrico / Polymorphisms in detoxification genes CYP1A1, CYP2E1, GSTT1 and GSTM1 in gastric cancer susceptibility

Cytochrome P450 (CYP) and glutathione S-transferase (GST) enzymes are involved in activation and detoxification of many potential carcinogens. Genetic polymorphisms in those enzymes have been found to influence the interindividual susceptibility to cancer. Some polymorphisms of those enzymes have been associated specifically with susceptibility to gastric cancer. We conducted a study in a Costa Rican population, where gastric cancer incidence and mortality rates are among the highest in the world. We investigated whether such variations affected the risk of developing gastric cancer. Subjects included 31 with gastric cancer, 58 controls with gastric injures others than cancer and 51 normal controls confirmed by X-rays (double-contrast) or endoscopic diagnostic. DNA from peripheral white blood cell was obtained from all subjects. Deletion of GSTT1 and GSTM1 was assessed by multiplex PCR and genotyping of CYP2E1 was performed using a PCR-based restriction fragment length polymorphism assay with the restriction enzyme PstI and the gene CYP1A1 using the restriction enzyme MspI The prevalence of CYP1A1 Msp1 polymorphism, GSTT1 and GSTM1 null genotype was similar in the three groups of individuals (p = 0.73, p = 0.88 y p = 0.89 respectively). Our findings suggest that the polymorphism CYP2E1 PstI could be associated with a reduced risk of having gastric cancer (OR = 0.09, IC95%:0.01 - 0.83).