title: Cigarette smoking and esophageal cancer risk: an evaluation based on a systematic review of epidemiologic evidence among the Japanese population.
abstract: OBJECTIVE
  Although cigarette smoking is considered as an important risk factor for esophageal cancer, the magnitude of the association might be varied among geographic areas. Therefore, we reviewed epidemiologic studies on the association between cigarette smoking and esophageal cancer among the Japanese population.
  
  
  METHODS
  Original articles were obtained from MEDLINE searched using PubMed or from searches of the Ichushi database, complemented by manual searches. Evaluation of associations was based on the strength of evidence ('convincing', 'probable', 'possible' or 'insufficient') and the magnitude of association ('strong', 'moderate', 'weak' or 'no association'), together with biological plausibility as previously evaluated by the International Agency for Research on Cancer.
  
  
  RESULTS
  We identified four cohort studies and 11 case-control studies. All cohort studies and eight case-control studies showed strong positive associations between esophageal cancer and cigarette smoking. All cohort studies and five case-control studies showed that cigarette smoking had dose-response relationships with esophageal cancer. Meta-analysis of 12 studies indicated that the summary estimate for ever smokers relative to never smokers was 3.01 (95% confidence interval: 2.30-3.94). Summary relative risk for current and former smokers relative to never smokers was 3.73 (2.16-6.43) and 2.21 (1.60-3.06), respectively.
  
  
  CONCLUSIONS
  We conclude that there is convincing evidence that cigarette smoking strongly increases the risk of esophageal cancer in the Japanese population.
authors: Division of Epidemiology and Prevention, Aichi Cancer Center Research Institute, Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors: Isao
authors: I
authors: Oze
authors: Keitaro
authors: K
authors: Matsuo
authors: Hidemi
authors: H
authors: Ito
authors: Kenji
authors: K
authors: Wakai
authors: Chisato
authors: C
authors: Nagata
authors: Tetsuya
authors: T
authors: Mizoue
authors: Keitaro
authors: K
authors: Tanaka
authors: Ichiro
authors: I
authors: Tsuji
authors: Akiko
authors: A
authors: Tamakoshi
authors: Shizuka
authors: S
authors: Sasazuki
authors: Manami
authors: M
authors: Inoue
authors: Shoichiro
authors: S
authors: Tsugane
mesh_terms: D004938:Esophageal Neoplasms / Q000453:epidemiology / Q000209:etiology*; D006801:Humans; D007564:Japan / Q000453:epidemiology; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*