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APHA Scientific Session and Event Listing

Recorded presentation

Shirley A.A. Beresford, PhD, Department of Epidemiology, University of Washington, Box 357236, Seattle, WA 98195-7236, (206) 543-9512, beresfrd@u.washington.edu, Karen C. Johnson, MD, MPH, Health Science Center, University of Tennessee, 920 Madison Building, Memphis, TN 38163, Cheryl Ritenbaugh, PhD, Department of Family and Community Medicine, University of Arizona, 1450 N Cherry Ave., Tucson, AZ 85721-5052, Linda G. Snetselaar, PhD, Department of Epidemiology, University of Iowa College of Public Health, 200 Hawkins Drive, Iowa City, IA 52242, and Garnet L. Anderson, PhD, WHI Clinical Coordinating Center, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N. M3-A410, Seattle, WA 98109.

In the early 1990s, sufficient evidence existed to support a primary prevention trial evaluating effects of a low-fat eating pattern on colorectal cancer risk. The Women's Health Initiative Randomized Controlled Dietary Modification Trial recruited 48,835 post-menopausal women aged 50-79 years from 40 Clinical Centers throughout the United States. Random assignment was to dietary modification intervention (40%) or comparison group (60%). The intensive behavioral modification program aimed to motivate and support large reductions in dietary fat, to increase vegetables and fruits, and to increase grain servings, by using group sessions, self-monitoring techniques and other tailored and targeted strategies. The women in the comparison group continued their usual eating pattern. Intervention group participants significantly reduced their percent energy from fat by 10.7% more than did the comparison group at one year and separation between groups was mostly maintained (8.1% at Year 6). Statistically significant increases in vegetable, fruit and grain servings were also made. There was no evidence that the intervention reduced the risk of invasive colorectal cancer during a follow-up period averaging 8.1 years. The incidence of colorectal cancer was 201 (0.13% per year) in the intervention and 279 (0.12% per year) in the comparison group (Hazard Ratio 1.08, 95% Confidence Interval: 0.90-1.29). Secondary analyses revealed potential interactions with baseline aspirin use, and combined estrogen-progestin use status. Colorectal exam rates, not protocol defined, were similar between the intervention and comparison groups. A low-fat eating pattern did not reduce the risk of colorectal cancer in postmenopausal women over 8.1 years of follow-up. This is the first primary prevention trial of colorectal cancer involving a dietary factor, and adds importantly to the evidence concerning total dietary fat.

Learning Objectives:

• Evaluate the contribution of this large randomized trial to public health understanding of the relationship between low fat dietary pattern and risk of colorectal cancer.
• Articulate a public health message for older women concerning dietary fat intake.
• List 5 main findings from the WHI dietary modification trial.

Keywords: Food and Nutrition, Cancer Prevention

Presenting author's disclosure statement:

Any relevant financial relationships? No

Recorded presentation