title: Cigarette smoking and the risk of ovarian cancer in the Japanese population: findings from the Japanese Collaborate Cohort study.
abstract: OBJECTIVE
  The many studies into the relation between cigarette smoking and the risk of ovarian cancer have produced inconsistent results. Here we investigated this relation using data from the Japan Collaborative Cohort Study for Evaluation of Cancer Risk, initiated in 1988.
  
  
  METHODS
  A self-administered questionnaire on smoking habits and other risk factors for cancer was completed by 34 639 Japanese women. After 7.6 years of follow up, 39 cases of ovarian cancer were available for analyses. Cox proportional-hazards models were used to compute relative risks (RR) and to adjust for confounders.
  
  
  RESULTS
  Relative to those who had never smoked, the RR of ovarian cancer were 1.63 (95% confidence interval [CI] = 0.21-12.50) for former smokers and 2.27 (95% CI = 0.85-6.08) for current smokers. Among current smokers, the RR were 1.48 (95% CI = 0.20-10.92), 5.56 (95% CI = 1.68-19.06), and 1.86 (95% CI = 0.25-14.30) among women who smoked <10, 10-19, and at least 20 pack-years ([number of cigarettes smoked per day/20] x number of years subject has smoked), respectively, relative to those who had never smoked. A test for trend was statistically significant (P = 0.044).
  
  
  CONCLUSIONS
  These data indicate that cigarette smoking increases the risk of developing ovarian cancer in the Japanese population.
authors.affiliation: Department of Preventive Medicine/Biostatistics and Medical Decision Making, Nagoya University Graduate School of Medicine, Nagoya, Japan. ytt-niwa@xg7.so-net.ne.jp
authors.forename: Yoshimitsu
authors.initials: Y
authors.lastname: Niwa
authors.forename: Kenji
authors.initials: K
authors.lastname: Wakai
authors.forename: Sadao
authors.initials: S
authors.lastname: Suzuki
authors.forename: Koji
authors.initials: K
authors.lastname: Tamakoshi
authors.forename: Yingsong
authors.initials: Y
authors.lastname: Lin
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yatsuya
authors.forename: Takaaki
authors.initials: T
authors.lastname: Kondo
authors.forename: Kazuko
authors.initials: K
authors.lastname: Nishio
authors.forename: Akio
authors.initials: A
authors.lastname: Yamamoto
authors.forename: Shinkan
authors.initials: S
authors.lastname: Tokudome
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Hamajima
authors.forename: Hideaki
authors.initials: H
authors.lastname: Toyoshima
authors.forename: Akiko
authors.initials: A
authors.lastname: Tamakoshi
mesh_terms: D000368:Aged; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007564:Japan; D008875:Middle Aged; D010051:Ovarian Neoplasms / Q000453:epidemiology* / Q000209:etiology; D016016:Proportional Hazards Models; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*