Exercise is one of the most important actions you can take to help guard against many types of cancer. Up to 1/3 of cancer-related deaths are due to obesity and a sedentary lifestyle, including two of the most common cancers in the United States, breast and colon cancer. Many people exercise to prevent heart disease, but exercise can also play a key role in preventing cancer. Most cancers are caused by lifestyle factors — not genes.
It’s easier than you think! A half hour of physical activity daily such as walking, slow swimming, leisurely bike riding or golfing without a cart will get you started. Here are some other ways to be more active:
Often people view exercise narrowly as a way to lose weight or to look better. These incentives can be effective, but exercise is really about a person taking charge of his or her health, preventing chronic diseases like cancer, and living longer.
More than two dozen studies have shown that women who exercise have a 30% to 40% lower risk of breast cancer than their sedentary peers. The female hormone estrogen seems to play a vital role. Women with high estrogen levels in their blood have increased the risk for breast cancer. Since exercise lowers blood estrogen, it helps lower a woman’s breast-cancer risk. Exercise also reduces other cancer-growth factors such as insulin. Even older women need to be concerned about estrogen because after menopause the hormone is produced by fat cells. Women who exercise have less fat and therefore produce less estrogen. With more than 150,000 new breast-cancer cases reported in the United States each year, preventing cancer through exercise is one of the best ways a woman can take charge of her health.
Exercise plays a dramatic role in preventing cancer of the colon and rectum. Nearly 150,000 Americans are diagnosed with colorectal cancer each year, and approximately 50,000 die from the disease. Encouragingly, more than three dozen studies show exercisers reduce their risk of colon cancer by 20% or more compared to sedentary people, and the benefits are seen in both men and women, although the effect is higher in men. Changes in digestive acids and other substances also occur with exercise, and these changes are believed to provide some protection from colon cancer. Decreases in body fat, insulin, and other growth factors also may contribute to exercisers’ lower colon-cancer risk. Current research is also uncovering new ways in which physical activity cuts cancer risk—from reducing chronic inflammation to improving DNA repair.