title: Low-fat dietary pattern and risk of colorectal cancer: the Women's Health Initiative Randomized Controlled Dietary Modification Trial.
abstract: BACKGROUND
  Observational studies and polyp recurrence trials are not conclusive regarding the effects of a low-fat dietary pattern on risk of colorectal cancer, necessitating a primary prevention trial.
  
  
  OBJECTIVE
  To evaluate the effects of a low-fat eating pattern on risk of colorectal cancer in postmenopausal women.
  
  
  METHODS
  The Women's Health Initiative Dietary Modification Trial, a randomized controlled trial conducted in 48,835 postmenopausal women aged 50 to 79 years recruited between 1993 and 1998 from 40 clinical centers throughout the United States.
  
  
  METHODS
  Participants were randomly assigned to the dietary modification intervention (n = 19,541; 40%) or the comparison group (n = 29,294; 60%). The intensive behavioral modification program aimed to motivate and support reductions in dietary fat, to increase consumption of vegetables and fruits, and to increase grain servings by using group sessions, self-monitoring techniques, and other tailored and targeted strategies. Women in the comparison group continued their usual eating pattern.
  
  
  METHODS
  Invasive colorectal cancer incidence.
  
  
  RESULTS
  A total of 480 incident cases of invasive colorectal cancer occurred during a mean follow-up of 8.1 (SD, 1.7) years. Intervention group participants significantly reduced their percentage of energy from fat by 10.7% more than did the comparison group at 1 year, and this difference between groups was mostly maintained (8.1% at year 6). Statistically significant increases in vegetable, fruit, and grain servings were also made. Despite these dietary changes, there was no evidence that the intervention reduced the risk of invasive colorectal cancer during the follow-up period. There were 201 women with invasive colorectal cancer (0.13% per year) in the intervention group and 279 (0.12% per year) in the comparison group (hazard ratio, 1.08; 95% confidence interval, 0.90-1.29). Secondary analyses suggested potential interactions with baseline aspirin use and combined estrogen-progestin use status (P = .01 for each). Colorectal examination rates, although not protocol defined, were comparable between the intervention and comparison groups. Similar results were seen in analyses adjusting for adherence to the intervention.
  
  
  CONCLUSIONS
  In this study, a low-fat dietary pattern intervention did not reduce the risk of colorectal cancer in postmenopausal women during 8.1 years of follow-up.
  
  
  BACKGROUND
  ClinicalTrials.gov Identifier: NCT00000611.
authors.affiliation: Department of Epidemiology, University of Washington, Seattle, WA 98195-7236, USA. beresfrd@u.washington.edu
authors.forename: Shirley A A
authors.initials: SA
authors.lastname: Beresford
authors.forename: Karen C
authors.initials: KC
authors.lastname: Johnson
authors.forename: Cheryl
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authors.lastname: Ritenbaugh
authors.forename: Norman L
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authors.lastname: Lasser
authors.forename: Linda G
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authors.forename: Henry R
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authors.lastname: Black
authors.forename: Garnet L
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authors.lastname: Anderson
authors.forename: Annlouise R
authors.initials: AR
authors.lastname: Assaf
authors.forename: Tamsen
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authors.lastname: Bassford
authors.forename: Deborah
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authors.lastname: Bowen
authors.forename: Robert L
authors.initials: RL
authors.lastname: Brunner
authors.forename: Robert G
authors.initials: RG
authors.lastname: Brzyski
authors.forename: Bette
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authors.lastname: Caan
authors.forename: Rowan T
authors.initials: RT
authors.lastname: Chlebowski
authors.forename: Margery
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authors.forename: Rosanne C
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authors.lastname: Harrigan
authors.forename: Jennifer
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authors.initials: D
authors.lastname: Heber
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authors.initials: BV
authors.lastname: Howard
authors.forename: Judith
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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: Jane Morley
authors.initials: JM
authors.lastname: Kotchen
authors.forename: Lewis H
authors.initials: LH
authors.lastname: Kuller
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: Cora E
authors.initials: CE
authors.lastname: Lewis
authors.forename: JoAnn E
authors.initials: JE
authors.lastname: Manson
authors.forename: Karen L
authors.initials: KL
authors.lastname: Margolis
authors.forename: Yasmin
authors.initials: Y
authors.lastname: Mossavar-Rahmani
authors.forename: Judith K
authors.initials: JK
authors.lastname: Ockene
authors.forename: Linda M
authors.initials: LM
authors.lastname: Parker
authors.forename: Michael G
authors.initials: MG
authors.lastname: Perri
authors.forename: Lawrence
authors.initials: L
authors.lastname: Phillips
authors.forename: Ross L
authors.initials: RL
authors.lastname: Prentice
authors.forename: John
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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: Marcia L
authors.initials: ML
authors.lastname: Stefanick
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: Evelyn
authors.initials: E
authors.lastname: Whitlock
mesh_terms: D000236:Adenoma / Q000453:epidemiology / Q000517:prevention & control; D000368:Aged; D001241:Aspirin / Q000627:therapeutic use; D003111:Colonic Polyps / Q000453:epidemiology / Q000517:prevention & control; D015179:Colorectal Neoplasms / Q000453:epidemiology / Q000517:prevention & control*; D018752:Diet, Fat-Restricted; D015914:Estrogen Replacement Therapy; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D016013:Likelihood Functions; D008875:Middle Aged; D017698:Postmenopause; D011322:Primary Prevention; D016016:Proportional Hazards Models; D012306:Risk; D012307:Risk Factors
chemical_list: D001241:Aspirin