Walking an hour a week cuts colon cancer risk

NEW YORK (Reuters Health) - A large new study confirms that physical activity reduces colon cancer risk.

While just an hour of walking a week seemed to protect against the disease, the more strenuously women exercised, the lower their risk, Dr. Kathleen Y. Wolin of Washington University School of Medicine in St. Louis and colleagues found.

"Our findings suggest that participation in lower intensity activities may be sufficient to reduce risk though more vigorous activity provides comparable or perhaps additional risk reduction," they write in the International Journal of Cancer.

Research showing that exercise reduces colon cancer risk has been "consistent and convincing," Wolin and her team say, but questions remain about the intensity of exercise necessary to reduce risk.

To investigate, they followed at 79,295 women, aged 40 to 65 years old, for 16 years, during which time 547 developed colon cancer. All were participating in the Nurse's Health Study.

Women who walked for 1 to 1.9 hours each week were 31 percent less likely to develop colon cancer than those who didn't walk at all, the researchers found. And women who exercised at moderate or vigorous intensity for more than 4 hours weekly were at 44 percent lower risk of colon cancer than those who exercised for less than an hour a week.

There was no link between exercising over the long term and colon cancer risk, but the researchers note that the number of long-term exercisers may have been too small to detect a relationship.

They conclude: "Leisure-time physical activity should be encouraged for all adults for health benefits, including colon cancer prevention."

SOURCE: International Journal of Cancer, December 15, 2007.