Background and Aim: Polymorphisms in methylenetetrahydrofolate reductase (MTHFR) are known to beassociated with predisposition for certain cancers. This study aimed to evaluate the effects of lifestyle factors,family history and genetic polymorphisms in MTHFR C677T and A1298C on rectal cancer risk and possibleinteractions with lifestyle factors in Northeast Thailand.
Methods: A hospital-based case-control study wasconducted during 2002-2006 with recruitment of 112 rectal cancer cases and 242 non-rectal cancer patient controls.Information was collected using a structured-questionnaire. Blood samples were obtained for assay of MTHFRC677T and A1298C genotypes by polymerase chain reaction with restriction fragment length polymorphism(PCR-RFLP) techniques. Associations between lifestyle factors, family history and genetic polymorphisms v.s.rectal cancer risk were assessed using logistic regression analysis.
Results: Subjects with frequent and occasionalconstipation had a higher risk (OR<sub>adj</sub>.=14.64; 95%CI=4.28-50.04 and OR<sub>adj</sub>.=2.15; 95%CI=1.14-4.06), along withthose who reported ever having hemorrhoids (OR<sub>adj</sub>.=2.82; 95%CI=1.36-5.84) or a family history of cancer(OR<sub>adj</sub>.=1.90; 95%CI=1.06-3.39). Consumption of a high level of pork was also associated with risk (OR<sub>adj</sub>.=1.82;95%CI=1.05-3.15). Interactions were not observed between MTHFR and other risk factors.
Conclusions: Thisstudy suggested that the risk factors for rectal cancer in the Thai population are bowel habits, having hadhemorrhoids, a family history of cancer and pork consumption.