Winter 2008

To Protect Against Cancer, Try a Little Exercise

BY COLLEEN STEELQUIST

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We all know that exercise is good for us. But what kind and how much?

As a cancer prevention researcher and very much a pragmatist, Dr. Anne McTiernan has no illusions about most folks’ commitment to exercise. She understands that people want to know exactly what they have to do—and how little they need to do—to reap healthy rewards.


Dr. Anne McTiernan
Twice a week, McTiernan gets up early and works out with a trainer. On other days, she bikes and walks for at least an hour. On weekends, she and her husband take a brisk walk in the park or hike in the mountains. For her, the workout routines represent a personal commitment to keeping diabetes at bay.

“I was diagnosed as pre-diabetic about five years ago, just about the time when three clinical trials came out showing that people who kept their weight down and were physically active could prevent diabetes,” she said. “For me, it was really helpful to have that information. Here’s something that works.”

“I think that’s going to be true for cancer as well,” she said, stressing that medical researchers now believe that 25 percent of all cancers may be caused by lack of physical activity and excess weight.

Thanks to McTiernan’s work, some specific answers now exist about the role of exercise and weight loss in reducing the risk of cancer. As director of the Hutchinson Center’s Prevention Center, she designs studies with the aim of reducing these cancers that come from sedentary lifestyles.

Fewer than one-quarter of Americans get minimum daily exercise, even though regular physical activity reduces body fat, lowers blood pressure, cholesterol and the risk of diabetes and cancer, and improves bone and joint health, sex drive, sleep and memory.

“We have such an epidemic of obesity and lack of exercise, which is one reason I’ve gravitated to exercise and weight control,” McTiernan said. “It’s an area of study that could have a significant impact.”

Exercise trials are uncommon because they’re expensive and difficult to fund. McTiernan’s group is the first to specifically look at the effects that increased physical activity and weight loss have on reducing risk factors for cancer.

Such risk reduction has been difficult to quantify in the past, but McTiernan has been able to definitely gauge impacts by measuring so-called biomarkers in the research participants.

Among her most important findings, overweight post-menopausal women who exercised for 45 minutes five days a week whittled away unhealthy belly fat and lowered their estrogen and testosterone levels, hormones that in excess can contribute to cancer.

In another study, women with breast cancer who walked leisurely just one to three hours a week lowered their risk of dying from the disease by one-quarter compared to sedentary women; those who walked three to eight hours weekly cut their risk in half. Another study showed that exercise six days a week brought both sexes significant fat loss and a lowered risk factor for colon cancer in men.

McTiernan’s groundbreaking work has put the Hutchinson Center at the forefront of the field, earning her an invitation to join a federal scientific advisory committee to develop the nation’s first guidelines to focus on physical activity—and the first to recognize the impact of exercise on cancer-risk reduction.

“We’re trying to get specific answers for people: do I need to lose 50 pounds or will 5 percent of my body weight do it? Will exercising 20 minutes a day help?” McTiernan said. “Nothing is guaranteed, but exercise and weight control are like wearing a seat belt. It reduces your risk.”

Government releases new guidelines for physical activity

In October, the United States Department of Health and Human Services published its most comprehensive report on physical activity, stressing that everyone would benefit from more exercise.

The Hutchinson Center’s Dr. Anne McTiernan served on the 13-member advisory committee that drafted the new guidelines. McTiernan said the guidelines should allow people to easily fit physical activity into their daily lives.

For the full report, visit, www.health.gov/paguidelines.


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