title: Coffee, tea, and caffeine consumption and breast cancer incidence in a cohort of Swedish women.
abstract: OBJECTIVE
  Coffee, caffeinated tea, and caffeine have been suggested to play a role in breast carcinogenesis or in the promotion or inhibition of tumor growth. Prior epidemiologic evidence has not supported an overall association between consumption of caffeinated beverages and risk of breast cancer, but consumption in some studies was low.
  
  
  METHODS
  We studied this relation in the Swedish Mammography Screening Cohort, a large population-based prospective cohort study in Sweden comprising 59,036 women aged 40-76 years. Sweden has the highest coffee consumption per capita in the world.
  
  
  RESULTS
  During 508,267 person-years of follow-up, 1271 cases of invasive breast cancer were diagnosed. Women who reported drinking 4 or more cups of coffee per day had a covariate-adjusted hazard ratio of breast cancer of 0.94 [95% confidence interval (CI) 0.75-1.28] compared to women who reported drinking 1 cup a week or less. The corresponding hazard ratio for tea consumption was 1.13 (95% CI 0.91-1.40). Similarly, women in the highest quintile of self-reported caffeine intake had a hazard ratio of beast cancer of 1.04 (95% CI 0.87-1.24) compared to women in the lowest quintile.
  
  
  CONCLUSIONS
  In this large cohort of Swedish women, consumption of coffee, tea, and caffeine was not associated with breast cancer incidence.
authors.affiliation: Obstetrics & Gynecology Epidemiology Center, Brigham & Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
authors.forename: Karin B
authors.initials: KB
authors.lastname: Michels
authors.forename: Lars
authors.initials: L
authors.lastname: Holmberg
authors.forename: Leif
authors.initials: L
authors.lastname: Bergkvist
authors.forename: Alicja
authors.initials: A
authors.lastname: Wolk
mesh_terms: D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000139:chemically induced / Q000453:epidemiology*; D002110:Caffeine / Q000009:adverse effects*; D003069:Coffee; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D011446:Prospective Studies; D013548:Sweden / Q000453:epidemiology; D013662:Tea
chemical_list: D003069:Coffee; D013662:Tea; D002110:Caffeine