How a major cancer study came to save the lives of thousands of women
By Ignacio Lobos, Hutchinson Center External Communications Editor
This month of July is extra special at the Hutchinson Center, with researchers and staff observing the 10th anniversary of a landmark study that has been responsible for reducing breast cancer cases by the tens of thousands—nearly a quarter of a million fewer cases since its publication in 2002.
Millions of women in the United States have the Women’s Health Initiative—one of the largest U.S. prevention studies of its kind—to thank for the findings that completely overturned what the medical community thought it knew about combination hormone replacement therapy.
When results of the study were released in July of 2002, more than 15 million postmenopausal women were receiving combination hormone replacement therapy to alleviate symptoms of menopause and to prevent fractures and heart attacks. Or so doctors thought. However, WHI data showed that the therapy significantly increased the risk of heart disease, stroke and breast cancer.
“It was a revolutionary set of findings that came out in that paper, said Dr. Andrea LaCroix, a member of the Public Health Sciences Division at the Hutchinson Center and a WHI investigator.
“That was a watershed moment after which many things changed with respect to hormone therapy and disease. Since then, women’s use of hormone therapy has plunged in the U.S. and many other countries, and this has been followed by measurable decreases in breast cancer in several countries and, in the U.S., decreases in heart attack and stroke,” she said.
The Hutchinson Center has played a pivotal role in WHI studies. Launched in 1991 with a $625 million grant from the National Institutes of Health, WHI quickly became one of the largest prevention studies, following the health of more than 161,000 postmenopausal women throughout the U.S.
The WHI’s Clinical Coordinating Center is housed at the Hutchinson Center and many of our researchers have played pivotal roles as WHI investigators. Seattle also is home to one of the WHI’s 40 clinical sites, coordinated jointly by the Hutchinson Center and University of Washington.
Of course, researchers would not have been able to glean all this important data without the tens of thousands of women who have participated in WHI studies. Today, more than 115,000 WHI participants continue to provide health information that is being used to investigate a variety of key women’s health questions.
At the Hutchinson Center, researchers are grateful that so many women continue to participate in WHI studies. Thanks to them—and their data—our researchers have made a number of other key findings, including:
- Dr. Ross Prentice and colleagues found that a low-fat diet may reduce the risk of ovarian cancer, as well as breast cancer.
- Dr. Anne McTiernan and colleagues found that postmenopausal women who exercise regularly and keep their weight within a normal range had the lowest levels of circulating estrogens—suggesting they may be at lower risk for breast cancer.
- In analyzing a trial of estrogen-only therapy in women who had a hysterectomy, Dr. Garnet Anderson and colleagues found that women who take estrogen by itself are less likely to develop breast cancer.
- Dr. Andrea LaCroix and colleagues found that taking calcium and vitamin D supplements increases bone mineral density and may reduce the risk of hip fractures and death.
- In analyses of genetic data for WHI participants, Dr. Charles Kooperberg and colleagues identified two new areas of the genome that were associated with body height in African American women.
Last year, the Hutchinson Center received a $55.4 million award from the National Heart, Lung and Blood Institute to continue coordinating the study through 2015. In the current phase, researchers are extending and refining the main clinical trial findings, identifying factors associated with healthy aging and searching for more ways to improve women’s health.
MORE INFORMATION: a hormone replacement therapy primer
Below are WHI’s findings on effects of two common types of hormone therapy on risks of various diseases in women. Estrogen plus progestin therapy is prescribed to postmenopausal women; estrogen alone is used in women who have had a hysterectomy. For more information, visit http://whi.org/ and http://whiscience.org.
If you take: Estrogen plus progestin, your risk of:
- Heart disease—increases
- Pulmonary embolism—increases
- Breast cancer—increases
- Colorectal cancer—may decrease
- Hip fracture—decreases
If you take estrogen alone:
- Heart disease—may increase or decrease depending on your age
- Pulmonary embolism—increases slightly
- Breast cancer—decreases (in some women)
- Colorectal cancer—does not change
- Hip fracture—decreases