title: [Relationship between N-nitrosodimethylamine and risk of digestive tract cancers: a Meta analysis based on cohort studies].
abstract: OBJECTIVE
  To analyze the relationship between N-nitrosodimethylamine(NDMA)and the risk of digestive tract cancers.
  
  
  METHODS
  The papers about the relationship between NDMA and the risk of digestive tract cancers published from 1980 to 2012 were retrieved following databases: Chinese BioMedical Literature Database(CBM), the Chinese Journal Full-text Database(CNKI), Wanfang Database, PubMed and EBSCO. The fix and random effect model was used and statistical analyses were conducted by using RevMan 5.1 software.
  
  
  RESULTS
  Thirteen papers were found, in which 7 about digestive tract cancers were used in this Meta analysis. The NDMA had significant positive effect on the incidence of digestive tract cancers(RR=1.12, 95% CI: 1.03-1.21). The relationship between NDMA and esophageal cancer was not significant(RR=1.18, 95%CI: 0.98-1.41)but NDMA could increase the risk of gastric cancer(RR=1.08, 95% CI: 1.00-1.18). For the subtypes of esophageal and gastric cancer, NDMA had positive relationship with esophageal squamous cell carcinoma(RR=1.72, 95% CI: 1.01-2.96), but had no significant relationship with esophageal adenocarcinoma, cardiac carcinoma and gastric adenocarcinoma.
  
  
  CONCLUSIONS
  The population-based cohort studies have showed that the NDMA could significantly increase the risk of digestive tract cancers, but the effects differed with subtypes of esophageal and gastric cancer. However, it is necessary to collect more evidence due to the limited studies and obvious differences in the study design, sampling and exposure measurement of these cohort studies.
authors.affiliation: National Center for Chronic and Non-communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
authors.forename: J
authors.initials: J
authors.lastname: Cui
authors.affiliation: Chinese Center for Disease Control and Prevention, Beijing 102206, China.
authors.forename: X M
authors.initials: XM
authors.lastname: Guo
authors.affiliation: National Center for Chronic and Non-communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
authors.forename: H L
authors.initials: HL
authors.lastname: Bao
authors.affiliation: Chinese Center for Disease Control and Prevention, Beijing 102206, China.
authors.forename: J B
authors.initials: JB
authors.lastname: Tan
mesh_terms: D000230:Adenocarcinoma; D044466:Asian People / Q000706:statistics & numerical data*; D002294:Carcinoma, Squamous Cell / Q000139:chemically induced / Q000453:epidemiology; D002681:China / Q000453:epidemiology; D015331:Cohort Studies; D004067:Digestive System Neoplasms / Q000139:chemically induced* / Q000209:etiology; D004128:Dimethylnitrosamine / Q000008:administration & dosage / Q000009:adverse effects*; D004938:Esophageal Neoplasms / Q000139:chemically induced / Q000453:epidemiology; D000077277:Esophageal Squamous Cell Carcinoma; D005770:Gastrointestinal Neoplasms / Q000139:chemically induced* / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D011159:Population Surveillance; D018570:Risk Assessment; D012307:Risk Factors; D013274:Stomach Neoplasms / Q000139:chemically induced
chemical_list: D004128:Dimethylnitrosamine