title: CYP2E1 genetic polymorphisms and risk of nasopharyngeal carcinoma in Taiwan.
abstract: BACKGROUND
  Nasopharyngeal carcinoma occurs disproportionately among individuals of Chinese descent. The cytochrome P450 2E1 enzyme (CYP2E1) is known to activate nitrosamines and other carcinogens that are possibly involved in the development of this disease. Certain alleles of the CYP2E1 gene are thought to be more highly expressed than others, and their distribution varies between Asian and Caucasian populations. We conducted a case-control study to investigate whether such variations affect the risk of developing nasopharyngeal cancer.
  
  
  METHODS
  Three hundred sixty-four patients with nasopharyngeal carcinoma (96% of 378 eligible patients) and 320 control subjects (86% of 374 eligible subjects) were studied. A risk factor questionnaire was administered to participants to assess factors postulated to be linked to nasopharyngeal carcinoma. Peripheral blood was obtained from all subjects and DNA was purified from nucleated cells. A polymerase chain reaction-based restriction fragment length polymorphism assay that used the restriction enzymes Rsa I and Dra I was used to detect wild-type and variant forms of the CYP2E1 gene.
  
  
  RESULTS
  Individuals homozygous for an allele of the CYP2E1 gene that is detected by Rsa I digestion (c2 allele) were found to have an increased risk of nasopharyngeal carcinoma (relative risk [RR] = 2.6; 95% confidence interval [CI] = 1.2-5.7); this effect was limited to nonsmokers (RR = 9.3; 95% CI = 2.7-32) and was not affected by alcohol consumption.
  
  
  CONCLUSIONS
  Our findings suggest that the CYP2E1 genotype is a determinant of nasopharyngeal carcinoma risk.
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, MD 20892, USA. Hildesha@epndce.nci.nih.gov
authors.forename: A
authors.initials: A
authors.lastname: Hildesheim
authors.forename: L M
authors.initials: LM
authors.lastname: Anderson
authors.forename: C J
authors.initials: CJ
authors.lastname: Chen
authors.forename: Y J
authors.initials: YJ
authors.lastname: Cheng
authors.forename: L A
authors.initials: LA
authors.lastname: Brinton
authors.forename: A K
authors.initials: AK
authors.lastname: Daly
authors.forename: C D
authors.initials: CD
authors.lastname: Reed
authors.forename: I H
authors.initials: IH
authors.lastname: Chen
authors.forename: N E
authors.initials: NE
authors.lastname: Caporaso
authors.forename: M M
authors.initials: MM
authors.lastname: Hsu
authors.forename: J Y
authors.initials: JY
authors.lastname: Chen
authors.forename: J R
authors.initials: JR
authors.lastname: Idle
authors.forename: R N
authors.initials: RN
authors.lastname: Hoover
authors.forename: C S
authors.initials: CS
authors.lastname: Yang
authors.forename: S K
authors.initials: SK
authors.lastname: Chhabra
mesh_terms: D000328:Adult; D000368:Aged; D000483:Alleles; D044466:Asian People / Q000235:genetics*; D002273:Carcinogens / Q000009:adverse effects; D016022:Case-Control Studies; D019392:Cytochrome P-450 CYP2E1 / Q000235:genetics*; D000431:Ethanol / Q000009:adverse effects; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000235:genetics*; D009602:Nitrosamines / Q000009:adverse effects; D011110:Polymorphism, Genetic; D012306:Risk; D012307:Risk Factors; D011795:Surveys and Questionnaires; D013624:Taiwan
chemical_list: D002273:Carcinogens; D009602:Nitrosamines; D000431:Ethanol; D019392:Cytochrome P-450 CYP2E1