Low-fat dietary pattern and risk of colorectal cancer: the Women's Health Initiative Randomized Controlled Dietary Modification Trial


Shirley A. A. Beresford, University of Washington - Seattle Campus
Karen C. Johnson, University of Tennessee
Cheryl Ritenbaugh, Kaiser Permanente Center for Health Research
Norman L. Lasser, University of California at San Diego
Linda G. Snetselaar
Henry R. Black, Rush University Medical Center
Garnet L. Anderson, Fred Hutchinson Cancer Research Center
Annlouise R. Assaf, Brown University
Tamsen Bassford, University of Arizona
Deborah J. Bowen, Fred Hutchinson Cancer Research Center
Robert L. Brunner, University of Nevada School of Medicine
Robert G. Brzyski, University of Texas
Bette J. Caan, Kaiser Permanente
Rowan T. Chlebowski, University of California
Margery Gass, University of Cincinnati College of Medicine
Rosanne C. Harrigan
Jennifer Hays, Baylor Medical College
David Heber, University of California
Gerardo Heiss, University of California
Susan L. Hendrix, Wayne State University School of Medicine
Barbara V. Howard, Medstar Research Institute
Judith Hsia, George Washington University
F. Allan Hubbell, University of California, Irvine
Rebecca D. Jackson, The Ohio State University
Jane Morley Kotchen, Medical College of Wisconsin
Lewis H. Kuller, University of Pittsburgh - Main Campus
Andrea Z. LaCroix, University of Washington
Robert D. Langer, Geisinger Health System
Cora E. Lewis, University of Alabama
JoAnn E. Manson, Harvard Medical School
Karen L. Margolis, HealthPartners Research Foundation
Yasmin Mossavar-Rahmani
Judith K. Ockene, University of Massachusetts Medical SchoolFollow
Linda M. Parker, University of Miami
Michael G. Perri, University of Florida
Lawrence Phillips, Emory University
Ross L. Prentice, Fred Hutchinson Cancer Research Center
John A. Robbins, University of California at Davis School of Medicine
Jacques E. Rossouw, National Heart, Lung, and Blood Institute
Gloria E. Sarto, University of Wisconsin–Madison
Marcia L. Stefanick, Stanford University
Linda Van Horn, Northwestern University
Mara Z. Vitolins, Wake Forest University School of Medicine
Jean Wactawski-Wende, State University of New York
Robert B. Wallace, University of Iowa
Evelyn Whitlock, Kaiser Permanente Center for Health Research

UMMS Affiliation

Department of Medicine, Division of Preventive and Behavioral Medicine

Publication Date


Document Type



Adenoma; Aged; Aspirin; Colonic Polyps; Colorectal Neoplasms; *Diet, Fat-Restricted; Estrogen Replacement Therapy; Female; Follow-Up Studies; Humans; Incidence; Likelihood Functions; Middle Aged; Postmenopause; Primary Prevention; Proportional Hazards Models; Risk; Risk Factors


Life Sciences | Medicine and Health Sciences | Women's Studies


CONTEXT: 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.

DESIGN, SETTING, AND PARTICIPANTS: 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.

INTERVENTIONS: 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.

MAIN OUTCOME MEASURE: 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.

CONCLUSION: 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.

CLINICAL TRIALS REGISTRATION: ClinicalTrials.gov Identifier: NCT00000611.

DOI of Published Version



JAMA. 2006 Feb 8;295(6):643-54. Link to article on publisher's site

Journal/Book/Conference Title

JAMA : the journal of the American Medical Association

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Link to article in PubMed

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