title: Risk factors for colon cancer in Northeastern Thailand: interaction of MTHFR codon 677 and 1298 genotypes with environmental factors.
abstract: BACKGROUND
  Polymorphisms in methylenetetrahydrofolate reductase (MTHFR), such as MTHFR C677T and A1298C, are associated with several cancers. This study aimed to evaluate the effects of MTHFR polymorphisms on colon cancer risk and possible interactions with environmental factors in a population from northeastern Thailand.
  
  
  METHODS
  This hospital-based case-control study was conducted during 2002-2006; 130 colon cancer cases and 130 age- and sex-matched controls were enrolled. Information was collected and blood samples were obtained for assay of MTHFR C677T and A1298C polymorphisms by polymerase chain reaction with restriction fragment length polymorphism techniques. Associations between variables of interest and colon cancer were assessed using conditional logistic regression.
  
  
  RESULTS
  Increased risk of colon cancer was associated with alcohol consumption and bowel habits. Alcohol drinkers who consumed < or = 0.50 or >0.50 units of alcohol per day had elevated risks (OR(adj) = 3.5; 95% CI: 1.19-10.25 and OR(adj) = 1.71; 95% CI: 0.74-3.96, respectively). The risk was also higher in subjects with frequent constipation (11.69; 2.18-62.79) and occasional constipation (3.43; 1.72-6.82). An interaction was observed between the MTHFR C677T polymorphism and freshwater fish consumption on colon cancer risk (P value for interaction = 0.031). Interactions were observed between the MTHFR A1298C polymorphism and bowel habits, family history of cancer, alcohol consumption, and beef consumption on colon cancer risk (P-value for interaction = 0.0005, 0.007, 0.067, 0.003, respectively).
  
  
  CONCLUSIONS
  In a Thai population, colon cancer risk was associated with alcohol and beef consumption, bowel habits, and family history of cancer. Interactions between MTHFR polymorphisms and environmental factors were also observed.
authors.affiliation: Department of Epidemiology, Faculty of Public Health, Khon Kaen University, Khon Kaen 40002, Thailand. supannee@kku.ac.th
authors.forename: Supannee Sriamporn
authors.initials: SS
authors.lastname: Promthet
authors.forename: Chamsai
authors.initials: C
authors.lastname: Pientong
authors.forename: Tipaya
authors.initials: T
authors.lastname: Ekalaksananan
authors.forename: Surapon
authors.initials: S
authors.lastname: Wiangnon
authors.forename: Kirati
authors.initials: K
authors.lastname: Poomphakwaen
authors.forename: Nopparat
authors.initials: N
authors.lastname: Songserm
authors.forename: Peechanika
authors.initials: P
authors.lastname: Chopjitt
authors.forename: Malcolm A
authors.initials: MA
authors.lastname: Moore
authors.forename: Shinkan
authors.initials: S
authors.lastname: Tokudome
mesh_terms: D000328:Adult; D000428:Alcohol Drinking / Q000453:epidemiology; D016022:Case-Control Studies; D003110:Colonic Neoplasms / Q000453:epidemiology / Q000235:genetics*; D003248:Constipation / Q000453:epidemiology; D004032:Diet / Q000706:statistics & numerical data; D004777:Environment; D005260:Female; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D016015:Logistic Models; D008297:Male; D042965:Methylenetetrahydrofolate Reductase (NADPH2) / Q000235:genetics*; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D012150:Polymorphism, Restriction Fragment Length; D012307:Risk Factors; D013785:Thailand / Q000453:epidemiology
chemical_list: D042965:Methylenetetrahydrofolate Reductase (NADPH2)