Walking for 30 minutes each day can lower the risk of dying from colon cancer. Credit: Washington University School of Medicine

Consistent exercise is associated with a lower risk of dying from colon cancer, according to a new study led by researchers at the Siteman Cancer Center at Washington University School of Medicine and Barnes-Jewish Hospital in St. Louis. The study is among the first to show that physical activity can make the disease less deadly.

The Washington University researchers worked with colleagues from the American Cancer Society and examined data from the American Cancer Society Prevention Study II (CPS II) to look at whether changes in physical activity influenced either the incidence of colon cancer diagnosis or the risk of death from the disease.

The CPS II study included more than 150,000 men and women. To determine how exercise affected colon cancer, the researchers compared their levels of physical activity between 1982 and 1997, and linked those activity levels both to the number of colon cancer diagnoses between 1998 and 2005, and to the number of colon cancer deaths that occurred between 1998 and 2006. It turned out that those who exercised consistently for at least 10 years had the lowest risk of colon cancer death.

"People who were consistently active over the course of their adulthood had a lower risk of death from colon cancer than those who were sedentary," says first author Kathleen Y. Wolin, ScD. "People often wonder around the start of a new year whether exercise really will help them stay healthy or whether it's already too late. It's never too late to start exercising, but it's also never too early to start being active. That's the message we hope people will take away from this study."

Wolin, assistant professor of surgery in the Division of Public Health Sciences, says the benefits of starting an exercise program include not just preventing colon cancer and death from the disease, but also reduced risk of heart disease, diabetes and other cancers.

She says the greatest benefits seem to accrue in those who have exercised for the largest percentage of their lives. But it isn't necessary to run marathons or to work out for many hours every day.

"You get enormous 'bang for the buck,'" she says. "You go for a 30-minute walk every day, and you're going to reduce your risk of a number of diseases. And in addition, our research has also shown that you feel better, physically and mentally, so you're able to function better."

And physical activity even can be beneficial after a cancer diagnosis already has been made.

"There is evidence that being physically active can reduce the risk of recurrence and death following a cancer diagnosis," Wolin says. "So even those who haven't been physically active can begin exercising after their diagnosis and see some real benefits as well."

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Wolin KY, Patel AV, Campbell PT, Jacobs EJ, McCullough ML, Colditz GA, Gapstur SM. Change in physical activity and colon cancer incidence and mortality, Cancer Epidemiology, Biomarkers & Prevention, vol. 19(12), pp. 3000-3004. Dec. 2010

Washington University School of Medicine: http://www.medicine.wustl.edu