Cancer: An Ounce of Prevention

If a woman is asked which disease she fears most, she's likely to single out breast cancer. Even though other diseases are far more common, the fear of breast cancer looms large.

But, in fact, the outlook for breast cancer has never been so optimistic. Modern treatments mean some 75 percent of breast cancer patients will survive 10 years after their initial diagnosis. Even more reassuring, studies show small changes in diet and exercise can significantly lower the risk that a woman will develop the disease at all.

A majority of breast cancer cases—about two-thirds—are hormonally driven, meaning that tumor growth is fueled by the body's own chemical messengers.

A study has found that moderate exercise—walking three to five hours per week—can reduce the risk of this type of breast cancer by half.

"If women are scared of breast cancer and they want to do something about it, exercise is it," says Michelle Holmes, a Harvard Medical School professor who co-authored the study. Women who exercise regularly have a 20 to 40 percent lower chance of developing breast cancer than women who don't.

"Walking is good," says Leslie Bernstein, a professor of preventive medicine at the University of Southern California. "But the more vigorous types of exercise—running, cycling, swimming—are better." Even women who have breast cancer can find relief in exercise. It combats many of the worst side-effects of chemotherapy: fatigue, pain, nausea,and depression.

The risk of genetic forms of cancer can also be altered by lifestyle. On top of the low-fat, high-fiber diet that protects against many types of disease, researchers also recommend olive oil as a preventative measure. People who eat the so-called Mediterranean diet, rich in olive oil, have about half the risk of breast cancer as people who eat a typical American diet. Forty to 50 grams of olive oil a day, about one serving of salad dressing, is enough to lower overall risk.