title: A prospective study of educational background and breast cancer among Japanese women.
abstract: OBJECTIVE
  This prospective cohort study examined the association between educational level and breast cancer incidence in Japan.
  
  
  METHODS
  A baseline survey was conducted between 1988 and 1990 among 110,792 residents of 45 areas, aged 40-79 years. Data were restricted to 24 areas where incidence registry data were available, and to subjects which provided information on educational level (32,646). The subjects were assigned to three groups according to their level of education (<16, 16-18, 18<). During 13 years of follow-up (328,931 person-year), 169 cases of breast cancer were newly diagnosed.
  
  
  RESULTS
  Women with a high level of education had an increased risk of breast cancer (HR = 1.93, 95 percent confidence interval (95% CI): 1.18, 3.16, in women with the highest educational level) compared with women with the lowest educational level. Adjustment for lifestyle and reproductive factors did not substantially change the results. In addition, when analyses were stratified by age subgroups, the educational difference in breast cancer incidence was more evident among the younger than the elder subgroup.
  
  
  CONCLUSIONS
  The present results suggested that cancer prevention strategies should recognize women with a higher educational level as a high risk group for breast cancer.
authors.affiliation: Department of Preventive Medicine and Community Health, University of Occupational and Environmental Health, 1-1, Iseigaoka, Yahatanishiku, Kitakyushu, Japan. zenq@med.uoeh-u.ac.jp
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Fujino
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Mori
authors.forename: Akiko
authors.initials: A
authors.lastname: Tamakoshi
authors.forename: Fumio
authors.initials: F
authors.lastname: Sakauchi
authors.forename: Sadao
authors.initials: S
authors.lastname: Suzuki
authors.forename: Kenji
authors.initials: K
authors.lastname: Wakai
authors.forename: Shinkan
authors.initials: S
authors.lastname: Tokudome
authors.forename: Takesumi
authors.initials: T
authors.lastname: Yoshimura
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000453:epidemiology*; D004522:Educational Status; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008875:Middle Aged; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012307:Risk Factors; D012959:Socioeconomic Factors