Women's Health Initiative Seattle Field Center

PI: Shirley Beresford PhD

The Women's Health Initiative, or WHI, is a multicenter study funded by the National Heart, Lung, and Blood Institute of the National Institutes of Health (NIH). Established by the NIH in 1991, the WHI involves 40 research institutions throughout the United States. Extended follow up of participants will continue through 2010.

The WHI Seattle Clinical Center, run jointly by Fred Hutchinson Cancer Research Center and the University of Washington, was one of the first of 16 clinical centers to be involved in the study.

The WHI had two components: a clinical trial and an observational study. Both followed women, who were aged 50-79 at the time of study enrollment, for nine years. The clinical trial tested the benefits and risks of hormone therapy, dietary modification, and calcium-plus-vitamin-D supplementation in relation to the overall health of post-menopausal women.

Participants were enrolled in one or multiple arms of the clinical trial or observational study. Primary study outcomes are coronary heart disease, breast and colorectal cancer, and hip fractures. The WHI Seattle Clinical Center began study enrollment in 1993 and is now in the extended follow-up phase. We enrolled more than 3,000 women into the study: 1,767 into the clinical trial and 1,662 into the observational study. Follow up contacts are initiated by the Clinical Coordinating Center, and backed up by the Field Center.

The active intervention phase of the Hormone Therapy trials ended earlier than planned: In July 2002, the arm of the study, that involved women with a uterus at the time of enrollment, who were randomized to take either placebo or estrogen plus progestin, asked participants to stop taking these pills. Estrogen plus progestin was demonstrated to have risks that exceed benefits. In April 2004, the arm that was studying the balance of risks and benefits of estrogen-alone therapy versus placebo, in women with a hysterectomy, also asked participants to stop taking the study hormone pills. This arm stopped because NIH concluded there was enough data to answer the main study question, and the balance of benefits and risks of estrogen alone was not likely to change further. The active intervention phase of the calcim-plus-vitamin D trial and of the dietary modification trial ended as planned in 2005.

Main study findings have been published. In the extended follow-up, women in the dietary modification trial are being encouraged to maintain their eating patterns as followed during the active intervention phase.

For more information about the Women's Health Initiative, see www.whi.org.

Contact: James Fraser
Seattle's Clinical Center
Fred Hutchinson Cancer Research Center
1100 Fairview Avenue North, MD-B141
Seattle, WA 98109
(206) 667-6551 phone
(206) 667-6550 fax

Reference:
Beresford SAA, Johnson KC, Ritenbaugh C, Et Al. Low-Fat Dietary Pattern and Risk of Colorectal Cancer: The Women's Health Initiative Randomized Controlled Dietary Modification Trial, JAMA, 295643-654, 2006.
Prentice RL, Caan B, Chlebowski RT, Et Al. Low-Fat Eating Pattern and Risk of Breast Cancer: The Women's Health Initiative Randomized Controlled Dietary Modification Trial. JAMA, 295(6)629-642, 2006.
Jackson RD, LaCroix AZ, Gass M, Et Al. Calcium plus vitamin D supplementation and the risk of fractures. N Engl J Med, 354(7)669-683, 2006.