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


Ross L. Prentice, Fred Hutchinson Cancer Research Center
Bette J. Caan, Kaiser Permanente
Rowan T. Chlebowski, University of California
Ruth E. Patterson, Fred Hutchinson Cancer Research Center
Lewis H. Kuller, University of Pittsburgh
Judith K. Ockene, University of Massachusetts Medical SchoolFollow
Karen L. Margolis, HealthPartners Research Foundation
Marian C. Limacher, University of Florida
JoAnn E. Manson, Harvard Medical School
Linda M. Parker, University of Miami
Electra Paskett, Ohio State University
Lawrence Phillips, Emory University
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
James M. Shikany, University of Alabama at Birmingham
Marcia L. Stefanick, Stanford University
Cynthia A. Thomson, University of Arizona
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
Sylvia Wassertheil-Smoller, Albert Einstein College of Medicine
Evelyn Whitlock, Kaiser Permanente Center for Health Research
Katsuhiko Yano, Kuakini Medical Center
Lucile L. Adams-Campbell, Howard Univeristy College of MedicineFollow
Garnet L. Anderson, Fred Hutchinson Cancer Research Center
Annlouise R. Assaf, Brown University
Shirley A. A. Beresford, University of Washington
Henry R. Black, Rush University Medical Center
Robert L. Brunner, University of Nevada School of Medicine
Robert G. Brzyski, University of Texas
Leslie Ford, National Cancer Institute
Margery Gass, University of Cincinnati College of Medicine
Jennifer Hays, Baylor Medical College
David Heber, University of California - Los Angeles
Gerardo Heiss, University of North Carolina
Susan L. Hendrix, Wayne State University School of Medicine
Judith Hsia, George Washington University
F. Allan Hubbell, University of California, Irvine
Rebecca D. Jackson, The Ohio State University
Karen C. Johnson, University of Tennessee
Jane Morley Kotchen, Medical College of Wisconsin
Andrea Z. LaCroix, University of Washington - Seattle Campus
Dorothy S. Lane, State University of New York
Robert D. Langer, Geisinger Health System
Norman L. Lasser, University of California at San Diego
Maureen M. Henderson, University of Medicine and Dentistry of New Jersey, Newark

UMMS Affiliation

Department of Medicine, Division of Preventive and Behavioral Medicine

Publication Date


Document Type



Aged; Biological Markers; Body Weight; Breast Neoplasms; Cholesterol, LDL; Diet Records; *Diet, Fat-Restricted; Female; Follow-Up Studies; Gonadal Steroid Hormones; Humans; Incidence; Middle Aged; Postmenopause; Primary Prevention; Proportional Hazards Models; Risk; Sex Hormone-Binding Globulin


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


CONTEXT: 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.

DESIGN AND SETTING: A randomized, controlled, primary prevention trial conducted at 40 US clinical centers from 1993 to 2005.

PARTICIPANTS: 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.

INTERVENTIONS: 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.

MAIN OUTCOME MEASURE: 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.

CLINICAL TRIALS REGISTRATION: ClinicalTrials.gov Identifier: NCT00000611.

DOI of Published Version



JAMA. 2006 Feb 8;295(6):629-42. 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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