title: Risk factors for cholangiocarcinoma in high-risk area of Thailand: role of lifestyle, diet and methylenetetrahydrofolate reductase polymorphisms.
abstract: OBJECTIVE
  Cholangiocarcinoma (CCA) is the most common cancer in Northeast Thailand. Endemicity of Opisthorchis viverrini (OV) - a known carcinogen - is responsible, but although infection is very common, the lifetime risk of CCA is only 5%. Other co-factors must exist, including aspects of lifestyle or diet along with variations in genetic susceptibility to them. Change in methylenetetrahydrofolate reductase (MTHFR) activity may influence both DNA methylation and synthesis. This study investigates risk factors for CCA with a focus on lifestyle, diet and MTHFR polymorphisms.
  
  
  METHODS
  Nested case-control study within cohort study was conducted. 219 subjects with primary CCA were each matched with two non-cancer controls from the same cohort on sex, age at recruitment and presence/absence of OV eggs in stool. Lifestyle and dietary data were obtained at recruitment. MTHFR polymorphisms were analyzed using PCR with high resolution melting analysis. The associations were assessed using conditional logistic regression.
  
  
  RESULTS
  Consumption of alcohol, raw freshwater fish and beef sausage increased the risk of CCA, while fruit and/or vegetables consumption reduced risk. There were interactions between MTHFR and preserved freshwater fish and beef. These dietary items are either a source of OV or of pre-formed nitrosamine, folate and antioxidants that are of possible relevance in OV carcinogenesis.
  
  
  CONCLUSIONS
  Primary prevention of CCA in high-risk population is based upon efforts to reduce OV infection. Reduced consumption of alcohol and preserved meats, and increased consumption of dietary folate, actions with a wider preventive potential, may also help in the reduction of CCA burden.
authors.affiliation: Department of Epidemiology, Faculty of Public Health, Khon Kaen University, Thailand. songsermn@hotmail.com
authors.forename: Nopparat
authors.initials: N
authors.lastname: Songserm
authors.forename: Supannee
authors.initials: S
authors.lastname: Promthet
authors.forename: Paiboon
authors.initials: P
authors.lastname: Sithithaworn
authors.forename: Chamsai
authors.initials: C
authors.lastname: Pientong
authors.forename: Tipaya
authors.initials: T
authors.lastname: Ekalaksananan
authors.forename: Peechanika
authors.initials: P
authors.lastname: Chopjitt
authors.forename: Donald Maxwell
authors.initials: DM
authors.lastname: Parkin
mesh_terms: D000328:Adult; D000368:Aged; D001650:Bile Duct Neoplasms / Q000453:epidemiology / Q000209:etiology* / Q000235:genetics; D001653:Bile Ducts, Intrahepatic / Q000473:pathology*; D016022:Case-Control Studies; D018281:Cholangiocarcinoma / Q000453:epidemiology / Q000209:etiology* / Q000235:genetics; D004032:Diet; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D008019:Life Style; D008297:Male; D042965:Methylenetetrahydrofolate Reductase (NADPH2) / Q000235:genetics*; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D060888:Real-Time Polymerase Chain Reaction; D012307:Risk Factors; D013785:Thailand
chemical_list: C573423:MTHFR protein, human; D042965:Methylenetetrahydrofolate Reductase (NADPH2)