title: Dietary patterns and breast cancer risk in a prospective Japanese study.
abstract: BACKGROUND
  The association between dietary patterns and breast cancer has been inconsistent.
  
  
  METHODS
  This study examined associations between dietary patterns and risk of developing breast cancer among 23,172 women from the Japan Collaborative Cohort Study, including 119 incidences of breast cancer diagnosed during a median 16.9-year follow-up period. Factor analysis was conducted to obtain dietary patterns, and Cox proportional models were used to estimate hazard ratios (HR) and 95 % confidence intervals (95 % CI) for breast cancer morbidity.
  
  
  RESULTS
  Three dietary patterns were identified: ''vegetable pattern'' (vegetables, potatoes, seaweed, tofu, fruits, fresh fish, eggs, and miso soup); ''animal food pattern'' (meat, deep-fried foods, fried vegetables, fish paste and salt-preserved fish); and "dairy product pattern'' (milk, dairy products, fruits, coffee and tea). After adjusting for potential confounders, the vegetable and dairy product patterns were not significantly associated with risk of breast cancer. However, the animal food pattern was significantly associated with a decreased risk of breast cancer morbidity among premenopausal women by HR 0.47 for the 2nd tertile (95 % CI 0.22-1.00) and HR 0.42 for the 3rd tertile (95 % CI 0.18-0.93), compared with the bottom tertile (p for trend 0.04).
  
  
  CONCLUSIONS
  We found no significant association between the vegetable and dairy product dietary patterns and breast cancer risk; however, an animal product diet may reduce risk of breast cancer among premenopausal Japanese women.
authors.affiliation: Department of Public Health, Hokkaido University Graduate School of Medicine, North 15 West 7 Kita-ku, Sapporo, 060-8638, Japan.|Department of Pediatrics, Japan Self-Defense Forces Sapporo Hospital, Hokkaido, 005-8543, Japan.
authors.forename: Reiji
authors.initials: R
authors.lastname: Kojima
authors.affiliation: Department of Public Health, Hokkaido University Graduate School of Medicine, North 15 West 7 Kita-ku, Sapporo, 060-8638, Japan.
authors.forename: Emiko
authors.initials: E
authors.lastname: Okada
authors.affiliation: Department of Public Health, Hokkaido University Graduate School of Medicine, North 15 West 7 Kita-ku, Sapporo, 060-8638, Japan. s-ukawa@med.hokudai.ac.jp.
authors.forename: Shigekazu
authors.initials: S
authors.lastname: Ukawa
authors.affiliation: Department of Public Health, School of Medicine, Sapporo Medical University, Hokkaido, 060-8556, Japan.
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Mori
authors.affiliation: Department of Preventive Medicine, Nagoya University Graduate School of Medicine, Nagoya, Aichi, 466-8550, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Wakai
authors.affiliation: Department of Food Science and Nutrition, School of Human Science and Environment, University of Hyogo, Hyogo, 670-0092, Japan.
authors.forename: Chigusa
authors.initials: C
authors.lastname: Date
authors.affiliation: Public Health, Department of Social and Environmental Medicine, Graduate School of Medicine, Osaka University, Osaka, 565-0871, Japan.
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Iso
authors.affiliation: Department of Public Health, Hokkaido University Graduate School of Medicine, North 15 West 7 Kita-ku, Sapporo, 060-8638, Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Tamakoshi
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000453:epidemiology / Q000209:etiology*; D003611:Dairy Products; D005163:Factor Analysis, Statistical; D005247:Feeding Behavior; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008460:Meat; D008875:Middle Aged; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012307:Risk Factors; D014675:Vegetables
keywords: Breast cancer; Cohort study; Dietary pattern; Japanese