title: Psychological attitudes and risk of breast cancer in Japan: a prospective study.
abstract: OBJECTIVE
  To examine the association between psychological factors and the risk of breast cancer prospectively in a non-Western population.
  
  
  METHODS
  Data from the Japan Collaborative Cohort (JACC) study were analyzed. From 1988 to 1990, 34,497 women aged 40-79 years completed a questionnaire on medical, lifestyle and psychosocial factors. The rate ratios (RRs) of their responses were computed by fitting to proportional hazards models.
  
  
  RESULTS
  During the mean follow-up period of 7.5 years, 149 breast cancer cases were documented. Those individuals who possessed "ikigai" (Japanese term meaning something that made one's life worth living) showed a significantly lower risk of breast cancer (multivariate-adjusted RR=0.66; 95% confidence interval [CI]=0.47-0.94). Those who perceived themselves as able to make decisions quickly also had a lower risk of breast cancer (multivariate-adjusted RR=0.56; 95% CI=0.36-0.87). The other factors investigated, including ease of anger arousal and self-perceived stress of daily life were not associated with breast cancer risk.
  
  
  CONCLUSIONS
  Although further studies will be necessary to verify these findings, our results suggest that having "ikigai" and being decisive decrease an individual's subsequent risk of breast cancer.
authors.affiliation: Division of Epidemiology and Prevention, Aichi Cancer Center Research Institute, 1-1 Kanokoden, Chikusa-ku, Nagoya, 464-8681, Japan. wakai@med.nagoya-u.ac.jp
authors.forename: Kenji
authors.initials: K
authors.lastname: Wakai
authors.forename: Masayo
authors.initials: M
authors.lastname: Kojima
authors.forename: Kazuko
authors.initials: K
authors.lastname: Nishio
authors.forename: Sadao
authors.initials: S
authors.lastname: Suzuki
authors.forename: Yoshimitsu
authors.initials: Y
authors.lastname: Niwa
authors.forename: Yingsong
authors.initials: Y
authors.lastname: Lin
authors.forename: Takaaki
authors.initials: T
authors.lastname: Kondo
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yatsuya
authors.forename: Koji
authors.initials: K
authors.lastname: Tamakoshi
authors.forename: Akio
authors.initials: A
authors.lastname: Yamamoto
authors.forename: Shinkan
authors.initials: S
authors.lastname: Tokudome
authors.forename: Hideaki
authors.initials: H
authors.lastname: Toyoshima
authors.forename: Akiko
authors.initials: A
authors.lastname: Tamakoshi
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000523:psychology*; D003657:Decision Making; D005260:Female; D006801:Humans; D007564:Japan; D008875:Middle Aged; D010549:Personal Satisfaction; D012307:Risk Factors; D013315:Stress, Psychological; D011795:Surveys and Questionnaires; D013694:Temperament