SEATTLE — June 4, 2001 — Why do couch potatoes face a significantly higher risk of colon cancer than those who are more physically active? Researchers at the Fred Hutchinson Cancer Research Center are embarking on the first study of its kind to find out.
This four-year, $6 million National Cancer Institute-funded initiative will investigate the reasons why moderate to vigorous exercise has been shown to lower the risk of developing colon polyps and colon cancer, a disease that strikes more than 100,000 Americans each year and kills 50,000.
Anne McTiernan, M.D., Ph.D., an international leader in research on exercise and cancer prevention, leads the effort.
"Epidemiologic studies that have measured physical activity indirectly have indicated that a higher activity level is associated with as much as a 50 percent reduction in colon-cancer risk," said McTiernan, an associate member of the Hutchinson Center's Public Health Sciences Division and a faculty member at the University of Washington schools of Medicine, and Public Health and Community Medicine. "We've observed an association between exercise and colon-cancer risk, even defined risk factors. Now we want to look at the mechanisms to explain these research results."
Called APPEAL (A Program Promoting Exercise and Active Lifestyles), the study seeks the participation of 200 healthy, sedentary Seattle-area men and women between the ages of 40 and 75. All must have undergone a colonoscopy within the past three years.
Half of the participants will be randomly assigned to an exercise group and half will serve as a control, or comparison, group. The exercisers will engage in moderate to vigorous physical activity six days a week for one year, working out both on their own and at an exercise facility under the supervision of a trainer. Those in the control group will be asked to maintain their current activity level for a year, after which they will have the opportunity to exercise for two months at no cost with a personal trainer at one of the study facilities.
Participants can choose to work out at the Washington Institute of Sports Medicine in Totem Lake or at a brand new, state-of-the-art exercise facility at the Hutchinson Center's Metropolitan Park campus in downtown Seattle. Equipment for this facility was provided through significant donations from The Seattle Foundation and Precor Inc. of Bothell.
All participants will undergo screening to rule out heart disease or other underlying conditions and ensure that it is safe for them to participate in a vigorous exercise program. If any cardiac irregularities are detected, participants will be referred to their primary-care provider for further evaluation.
Before and after completion of the intervention, participants also must undergo a flexible sigmoidoscopy, a procedure that allows for visual inspection of the rectum and lower colon, and the collection of tissue samples from the mucosal lining of the colon. This procedure will be performed at Harborview Medical Center or the Seattle Cancer Care Alliance.
"Basically, we want to examine the amount of cell growth and cell death. occurring at the lining of the intestine," said study coordinator Angela Morgan. "Polyp formation is a sign that there is excessive growth and too little cell death. We want to determine if the balance between these parameters becomes more normal after the exercise intervention."
In addition to assessing cell growth and cell death, researchers will track the effect of exercise on other markers for colon-cancer risk, from frequency of bowel function to the production of a hormone called prostaglandin E2, which at increased levels has been associated with the formation of colon polyps.
While the connection between exercise and colon cancer is not new, it is unclear whether exercise itself is responsible for the reduced risk, or whether it's because people who exercise tend to eat healthier foods and live generally healthier lives.
"There have been a lot of observational studies demonstrating that exercise can reduce colon-cancer risk," Morgan said. "But it hasn't been clear in those studies whether other lifestyle factors might be involved. APPEAL is the first study to look at the direct effect of exercise on certain risk factors associated with the formation of colon polyps and colon cancer."
Those who would like to participate can call the APPEAL study information line at (206) 667-6444.
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Fred Hutchinson Cancer Research Center
Fred Hutchinson Cancer Research Center, home of three Nobel laureates, is an independent, nonprofit research institution dedicated to the development and advancement of biomedical technology to eliminate cancer and other potentially fatal diseases. Recognized internationally for its pioneering work in bone-marrow transplantation, the center's four scientific divisions collaborate to form a unique environment for conducting basic and applied science. Fred Hutchinson, in collaboration with its clinical and research partners, UW Medicine and Children's Hospital and Regional Medical Center, is the only National Cancer Institute-designated comprehensive cancer center in the Pacific Northwest and is one of 40 nationwide. For more information, visit the center's website at www.fhcrc.org.