RESUMO
BACKGROUND: High meat intake and low consumption of vegetables, fruits and whole grains have been associated with increased risk of colorectal cancer in some relevant cohort studies conducted in distinct ethnic populations. The role of the dietary pattern on the risk of sporadic colorectal adenocarcinoma (SCA) in Brazil is unknown; therefore, it was the aim of the present study. METHODS: The dietary patterns of 169 patients with SCA and 101 controls were analysed by food frequency recall. Crude odds ratios were calculated and given within 95 % confidence intervals. RESULTS: Patients reported higher average intakes of beef (32.0 ± 1.8 versus 23.7 ± 1.6, P = 0.0069), chicken (18.1 ± 0.9 versus 12.2 ± 0.8, P = 0.0002), and pork (8.9 ± 0.9 versus 3.4 ± 0.5, P < 0.0001). These individuals had a 1.025, 1.069, and 1.121-fold increased risk of SCA. Similar consumption of fish, vegetables, fruits and whole grains was reported by patients and controls. CONCLUSIONS: Meat consumption is greater in patients with SCA in the Brazilian population. Considering the study population - characterized by ethnic heterogeneity -, the environmental factor related to food habits may be associated with higher incidence of this disease in Brazil.
Assuntos
Neoplasias Colorretais/epidemiologia , Dieta , Comportamento Alimentar , Adulto , Idoso , Idoso de 80 Anos ou mais , Brasil/epidemiologia , Estudos de Casos e Controles , Feminino , Frutas , Humanos , Incidência , Masculino , Carne , Pessoa de Meia-Idade , Fatores de Risco , Verduras , Grãos IntegraisRESUMO
5-Fluorouracil (5-FU) represents the basis of chemotherapy for colorectal carcinoma, inhibiting thymidylate synthase (TS), an essential enzyme for DNA replication. Previous studies have associated high TS protein expression by tumor cells with poor outcome of patients with colorectal carcinoma, but others have refuted these findings. In view of the potential role of TS as predictive parameter and the lack of consensus in the literature, the present study compared 2 methods: protein expression and gene polymorphism, correlating them with clinicopathological findings. Immunohistochemical detection of TS in tumor cells and detection of gene polymorphism in the blood were performed in 32 patients with colorectal carcinoma treated with 5-FU. No correlation was found between TS protein expression and gene polymorphism. Neither method correlated with survival, tumor staging, and tumor histological grading. This result possibly reflects a complex tumor response to 5-FU therapy, where TS is just one of the involved proteins.
Assuntos
Neoplasias Colorretais/enzimologia , Neoplasias Colorretais/genética , Polimorfismo Genético , Timidilato Sintase/biossíntese , Timidilato Sintase/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Antineoplásicos/uso terapêutico , Biomarcadores Tumorais/análise , Neoplasias Colorretais/tratamento farmacológico , Feminino , Fluoruracila/uso terapêutico , Humanos , Imuno-Histoquímica , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Reação em Cadeia da Polimerase , Prognóstico , Estudos Retrospectivos , Análise de SobrevidaRESUMO
Exposure to benzene has been associated with haematological diseases such as neutropenia (NEB) and acute myeloid leukaemia (AML). We tested whether the null genotypes of the GSTM1 and GSTT1 genes, involved in benzene inactivation, altered the risk for NEB in southeastern Brazil. Genomic DNA from 55 NEB patients and 330 controls was analysed by multiplex-polymerase chain reaction. The frequency of the GSTM1, GSTT1 and combined null genotypes was similar in patients and controls (GSTM1, 27.3% vs. 38.8%, p = 0.16; GSTT1, 25.5% vs. 19.7%, p = 0.24; GSTM1/GSTT1, 12.7% vs. 6.7%, p = 0.26; respectively). The distribution of genotype classes in NEB patients was similar to normal controls, suggesting that GSTM1 and GSTT1 null genotypes make no specific contribution to the risk of NEB. As the GSTM1 and GSTT1 null genotypes were previously associated with increased risk for AML in Brazil and elsewhere, we hypothesise that different thresholds of chemical exposure relative to distinct GSTM1 and GSTT1 genotypes may determine whether AML or NEB manifests in benzene exposed individuals from southeastern Brazil. Although indicative, our results still require support by prospective and large scale epidemiological studies, with rigorous assessment of daily chemical exposures and control of the possible contribution of other polymorphic genes involved in benzene metabolism.
RESUMO
Exposure to benzene has been associated with haematological diseases such as neutropenia (NEB) and acute myeloid leukaemia (AML). We tested whether the null genotypes of the GSTM1 and GSTT1 genes, involved in benzene inactivation, altered the risk for NEB in southeastern Brazil. Genomic DNA from 55 NEB patients and 330 controls was analysed by multiplex-polymerase chain reaction. The frequency of the GSTM1, GSTT1 and combined null genotypes was similar in patients and controls (GSTM1, 27.3 percent vs. 38.8 percent, p = 0.16; GSTT1, 25.5 percent vs. 19.7 percent, p = 0.24; GSTM1/GSTT1, 12.7 percent vs. 6.7 percent, p = 0.26; respectively). The distribution of genotype classes in NEB patients was similar to normal controls, suggesting that GSTM1 and GSTT1 null genotypes make no specific contribution to the risk of NEB. As the GSTM1 and GSTT1 null genotypes were previously associated with increased risk for AML in Brazil and elsewhere, we hypothesise that different thresholds of chemical exposure relative to distinct GSTM1 and GSTT1 genotypes may determine whether AML or NEB manifests in benzene exposed individuals from southeastern Brazil. Although indicative, our results still require support by prospective and large scale epidemiological studies, with rigorous assessment of daily chemical exposures and control of the possible contribution of other polymorphic genes involved in benzene metabolism.
RESUMO
BACKGROUND AND AIMS: Evidence is accumulating for a role of folate in the aetiology of colorectal cancer (CRC). The methylenetetrahydrofolate reductase (MTHFR) gene, involved in folate metabolism, is polymorphic in humans. Since it is unknown whether the MTHFR C677T and A1298C polymorphisms alter the risk for CRC, this was the aim of our study. MATERIALS AND METHODS: Genomic DNA from 102 sporadic colorectal adenocarcinoma (SCA) patients and 300 controls was analyzed by polymerase chain reaction followed by restriction digestion for the polymorphisms analyses. RESULTS/FINDINGS: The frequencies of MTHFR C677T and A1298C genotypes were similar in patients and controls. Similar overall risks for disease were seen in individuals with the distinct MTHFR genotypes. However, an excess of the MTHFR 677TT and 677CT genotypes was seen in patients under 50 years, compared with patients at an older age (19.2 vs 13.1% and 61.6 vs 39.5%, respectively; P = 0.04). The differences were more prominent when the frequency of the 677TT plus 677CT genotype was seen in both group of patients (80.8 vs 52.6%, respectively; P = 0.01), and in younger patients compared to controls (80.8 vs 52.3%, P < 0.01). Individuals with the combined genotype had 3.82-fold (95% confidence interval, 1.41-10.42) increased risk of developing SCA under 50 years, compared with those harboring the wild-type genotype. INTERPRETATION/CONCLUSION: These results suggest a role for the MTHFR 677TT plus 677CT genotype in increasing SCA diagnosed at a low age in southeastern Brazil, but additional studies with larger sample sizes should be carried out to clarify this issue.
Assuntos
Adenocarcinoma , Neoplasias Colorretais , DNA de Neoplasias/genética , Metilenotetra-Hidrofolato Redutase (NADPH2)/genética , Polimorfismo Genético , Adenocarcinoma/epidemiologia , Adenocarcinoma/genética , Adenocarcinoma/patologia , Fatores Etários , Idade de Início , Biomarcadores Tumorais/genética , Neoplasias Colorretais/epidemiologia , Neoplasias Colorretais/genética , Neoplasias Colorretais/patologia , Feminino , Genótipo , Humanos , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Reação em Cadeia da Polimerase , Prognóstico , Estudos Retrospectivos , Fatores de RiscoRESUMO
INTRODUCTION: Glutathione S-transferase enzymes mediate exposure to cytotoxic and genotoxic agents and may be involved in cancer susceptibility. Both glutathione S-transferase mu 1 (GSTM1) and GST theta 1 (GSTT1) genes have a null variant allele in which the entire gene is absent. The association of glutathione S-transferase null genotype and risk of developing colorectal cancer is not yet fully clarified. METHODS: We tested whether the null genotypes for GSTM1 and GSTT1 genes altered the risk for sporadic colorectal adenocarcinoma in Brazilian patients. Genomic DNA from 102 sporadic colorectal adenocarcinoma patients and 300 controls was analyzed by polymerase chain reaction. RESULTS: Frequencies of GSTM1, GSTT1, and null combined genotypes were similar in patients and controls (49.9 vs. 44.6 percent, 16.6 vs. 17.3 percent, and 8.8 vs. 8 percent, respectively). We found a 1.03-fold (95 percent confidence interval, 0.96-1.10) and 1.08-fold (95 percent confidence interval, 0.99-1.18) increased risk associated with GSTM1 and GSTT1 null genotypes, respectively (P = 0.45 and P = 0.08) and a 1.18-fold (95 percent confidence interval, 0.47-2.90) increased risk associated with the combined null genotype (P = 0.74). The GSTT1 null genotype was more common in patients who were diagnosed before the age of 60 years than in those who were diagnosed at an older age (28.8 vs. 4 percent, respectively; P = 0.0008). CONCLUSIONS: The results suggest that inherited absence of this carcinogen detoxification pathway may not be associated with sporadic colorectal adenocarcinoma in the present cases. However, a higher frequency of GSTT1 null genotype in patients diagnosed before the age of 60 years suggests that this genotype could influence the age of disease onset in Brazil.