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Can exercise help prevent cancer?

If you need a reason to begin an exercise program, this may be the news to get you up and running.

Regular, moderate physical activity plays a role in preventing or delaying the development of certain cancers, including cancers of the breast, cervix, uterus, vagina, prostate, colon and lungs.

The link between exercise and breast-cancer risk, for instance, has received a lot of attention. A 2003 study conducted by researchers at the Fred Hutchinson Cancer Research Center in Seattle found that women who engaged in regular, moderate physical activity were about 20 percent less likely to develop breast cancer than sedentary women.

Leading an active life may help your body fight cancer in several ways. One theory is that physically active people regularly produce higher levels of “natural killer” blood cells (NK-cells). These white blood cells are believed to be one of the immune system’s primary defenses against cancer. NK-cells aside, it’s true that physically fit, active people have stronger immune systems, which also lowers their odds of getting cancer.

Another way that exercise helps fight cancer is by speeding up metabolism. An increased metabolic rate quickly and effectively eliminates toxins through the kidneys, liver, skin and colon. Exercise also causes digestive wastes to flow through the colon more quickly, giving potential cancer-causing agents less time to make contact with sensitive colon tissue.

In women, the hormone estrogen has been linked to breast-tumor production. It triggers cells in the breast to divide. (It has a similar effect on the lining of the uterus, which can lead to uterine cancer.) The more cells divide, the higher the risk that a malignancy will develop. Exercise is thought to reduce a woman’s exposure to estrogen, thus reducing her risk of cancer.

The message is clear: Exercise is a simple way to keep yourself healthy. Not only can it protect you from illnesses such as heart disease, diabetes and osteoporosis, but it can reduce your risk of cancer as well.