One hour a day of vigorous physical activity or two hours of moderate activity reduces the risk of colon cancer, European researchers say.

Christine Friedenreich of the International Agency for Research on Cancer in Lyon, France, and the Alberta Cancer Board studied more than 413,000 people in 10 European countries to assess how physical activity can cut the risk of colon tumours.

"This is a very large study, which should remove any doubt about the benefits of exercise in relation to reducing the risk of bowel cancer," said Dr. Lesley Walker, Cancer Research U.K.'s director of information, which funded the study published on Monday.

"It is important for people to understand that they can take steps in their daily routine to reduce cancer risk. You don't need to join a gym to get the benefit of exercise."

Strenuous housework such as using a vacuum cleaner, scrubbing the bath tub and cleaning windows burns calories, and when combined with a healthy diet and body weight, can reduce the risk of bowel cancer, Walker said.

The study by the European Prospective Investigation into Cancer and Nutrition found people with the highest levels of exercise were 22 per cent less likely to develop colon cancer.

For tumours on the right side of the colon, the risk was reduced by up to 35 per cent in the most active people.

People of normal weight obtained the greatest risk reduction through exercise, but adults who were overweight or obese also obtained benefits.

Approximately 20,000 new cases of colorectal cancer will be diagnosed in Canada this year. Around 8,500 Canadians will die from the disease every year.

Health experts estimate about half of all cancers could be prevented by lifestyle changes such as quitting smoking, staying in shape, eating a healthy diet and avoiding the sun's harmful UV rays.