title: Low-fat dietary pattern and risk of invasive breast cancer: the Women's Health Initiative Randomized Controlled Dietary Modification Trial.
abstract: BACKGROUND
  The hypothesis that a low-fat dietary pattern can reduce breast cancer risk has existed for decades but has never been tested in a controlled intervention trial.
  
  
  OBJECTIVE
  To assess the effects of undertaking a low-fat dietary pattern on breast cancer incidence.
  
  
  METHODS
  A randomized, controlled, primary prevention trial conducted at 40 US clinical centers from 1993 to 2005.
  
  
  METHODS
  A total of 48,835 postmenopausal women, aged 50 to 79 years, without prior breast cancer, including 18.6% of minority race/ethnicity, were enrolled.
  
  
  METHODS
  Women were randomly assigned to the dietary modification intervention group (40% [n = 19,541]) or the comparison group (60% [n = 29,294]). The intervention was designed to promote dietary change with the goals of reducing intake of total fat to 20% of energy and increasing consumption of vegetables and fruit to at least 5 servings daily and grains to at least 6 servings daily. Comparison group participants were not asked to make dietary changes.
  
  
  METHODS
  Invasive breast cancer incidence.
  
  
  RESULTS
  Dietary fat intake was significantly lower in the dietary modification intervention group compared with the comparison group. The difference between groups in change from baseline for percentage of energy from fat varied from 10.7% at year 1 to 8.1% at year 6. Vegetable and fruit consumption was higher in the intervention group by at least 1 serving per day and a smaller, more transient difference was found for grain consumption. The number of women who developed invasive breast cancer (annualized incidence rate) over the 8.1-year average follow-up period was 655 (0.42%) in the intervention group and 1072 (0.45%) in the comparison group (hazard ratio, 0.91; 95% confidence interval, 0.83-1.01 for the comparison between the 2 groups). Secondary analyses suggest a lower hazard ratio among adherent women, provide greater evidence of risk reduction among women having a high-fat diet at baseline, and suggest a dietary effect that varies by hormone receptor characteristics of the tumor.
  
  
  CONCLUSIONS
  Among postmenopausal women, a low-fat dietary pattern did not result in a statistically significant reduction in invasive breast cancer risk over an 8.1-year average follow-up period. However, the nonsignificant trends observed suggesting reduced risk associated with a low-fat dietary pattern indicate that longer, planned, nonintervention follow-up may yield a more definitive comparison.
  
  
  BACKGROUND
  ClinicalTrials.gov Identifier: NCT00000611.
authors.affiliation: Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, Wash 98109, USA. rprentice@whi.org
authors.forename: Ross L
authors.initials: RL
authors.lastname: Prentice
authors.forename: Bette
authors.initials: B
authors.lastname: Caan
authors.forename: Rowan T
authors.initials: RT
authors.lastname: Chlebowski
authors.forename: Ruth
authors.initials: R
authors.lastname: Patterson
authors.forename: Lewis H
authors.initials: LH
authors.lastname: Kuller
authors.forename: Judith K
authors.initials: JK
authors.lastname: Ockene
authors.forename: Karen L
authors.initials: KL
authors.lastname: Margolis
authors.forename: Marian C
authors.initials: MC
authors.lastname: Limacher
authors.forename: JoAnn E
authors.initials: JE
authors.lastname: Manson
authors.forename: Linda M
authors.initials: LM
authors.lastname: Parker
authors.forename: Electra
authors.initials: E
authors.lastname: Paskett
authors.forename: Lawrence
authors.initials: L
authors.lastname: Phillips
authors.forename: John
authors.initials: J
authors.lastname: Robbins
authors.forename: Jacques E
authors.initials: JE
authors.lastname: Rossouw
authors.forename: Gloria E
authors.initials: GE
authors.lastname: Sarto
authors.forename: James M
authors.initials: JM
authors.lastname: Shikany
authors.forename: Marcia L
authors.initials: ML
authors.lastname: Stefanick
authors.forename: Cynthia A
authors.initials: CA
authors.lastname: Thomson
authors.forename: Linda
authors.initials: L
authors.lastname: Van Horn
authors.forename: Mara Z
authors.initials: MZ
authors.lastname: Vitolins
authors.forename: Jean
authors.initials: J
authors.lastname: Wactawski-Wende
authors.forename: Robert B
authors.initials: RB
authors.lastname: Wallace
authors.forename: Sylvia
authors.initials: S
authors.lastname: Wassertheil-Smoller
authors.forename: Evelyn
authors.initials: E
authors.lastname: Whitlock
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Yano
authors.forename: Lucile
authors.initials: L
authors.lastname: Adams-Campbell
authors.forename: Garnet L
authors.initials: GL
authors.lastname: Anderson
authors.forename: Annlouise R
authors.initials: AR
authors.lastname: Assaf
authors.forename: Shirley A A
authors.initials: SA
authors.lastname: Beresford
authors.forename: Henry R
authors.initials: HR
authors.lastname: Black
authors.forename: Robert L
authors.initials: RL
authors.lastname: Brunner
authors.forename: Robert G
authors.initials: RG
authors.lastname: Brzyski
authors.forename: Leslie
authors.initials: L
authors.lastname: Ford
authors.forename: Margery
authors.initials: M
authors.lastname: Gass
authors.forename: Jennifer
authors.initials: J
authors.lastname: Hays
authors.forename: David
authors.initials: D
authors.lastname: Heber
authors.forename: Gerardo
authors.initials: G
authors.lastname: Heiss
authors.forename: Susan L
authors.initials: SL
authors.lastname: Hendrix
authors.forename: Judith
authors.initials: J
authors.lastname: Hsia
authors.forename: F Allan
authors.initials: FA
authors.lastname: Hubbell
authors.forename: Rebecca D
authors.initials: RD
authors.lastname: Jackson
authors.forename: Karen C
authors.initials: KC
authors.lastname: Johnson
authors.forename: Jane Morley
authors.initials: JM
authors.lastname: Kotchen
authors.forename: Andrea Z
authors.initials: AZ
authors.lastname: LaCroix
authors.forename: Dorothy S
authors.initials: DS
authors.lastname: Lane
authors.forename: Robert D
authors.initials: RD
authors.lastname: Langer
authors.forename: Norman L
authors.initials: NL
authors.lastname: Lasser
authors.forename: Maureen M
authors.initials: MM
authors.lastname: Henderson
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood; D001835:Body Weight; D001943:Breast Neoplasms / Q000453:epidemiology / Q000517:prevention & control*; D008078:Cholesterol, LDL / Q000097:blood; D015930:Diet Records; D018752:Diet, Fat-Restricted; D005260:Female; D005500:Follow-Up Studies; D012739:Gonadal Steroid Hormones / Q000097:blood; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D017698:Postmenopause; D011322:Primary Prevention; D016016:Proportional Hazards Models; D012306:Risk; D012738:Sex Hormone-Binding Globulin / Q000032:analysis
chemical_list: D015415:Biomarkers; D008078:Cholesterol, LDL; D012739:Gonadal Steroid Hormones; D012738:Sex Hormone-Binding Globulin