Risk factors for colon cancer in Northeastern Thailand: interaction of MTHFR codon 677 and 1298 genotypes with environmental factors.
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.
Promthet
Supannee Sriamporn
SS
Department of Epidemiology, Faculty of Public Health, Khon Kaen University, Khon Kaen 40002, Thailand. supannee@kku.ac.th
Pientong
Chamsai
C
Ekalaksananan
Tipaya
T
Wiangnon
Surapon
S
Poomphakwaen
Kirati
K
Songserm
Nopparat
N
Chopjitt
Peechanika
P
Moore
Malcolm A
MA
Tokudome
Shinkan
S
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
D042965:Methylenetetrahydrofolate Reductase (NADPH2)