Is Exercise a Weapon Against Cancer?

If you have cancer and are undergoing chemotherapy, exercise is one of the best ways to combat treatment-related fatigue, and may even increase the body’s ability to recover from the effects of chemotherapy.

Several groundbreaking studies suggest that exercise doesn’t just help combat treatment-related fatigue, it may help fight against cancer. And obsessive exercise isn’t needed to see a benefit. Depending on the intensity of the activity, you may need to exercise only a few hours a week.

Researchers measured how much energy exercisers expended in metabolic equivalent task (MET) hours. One MET hour is the equivalent of the energy expended by the body during one hour of rest. You can rack up several MET hours of exercise during one “real-time” hour. For example, one hour of moderate walking is the equivalent of three MET hours and one hour of doubles tennis or slow jogging is the equivalent of 5 MET hours.

• The first study, published in the Journal of the American Medical Association, followed 2,987 women with breast cancer. Women who exercised more than three MET hours a week after diagnosis were less likely to die of their cancer.

• In another study of 573 women with colon cancer, women who exercised more than 18 MET hours a week after diagnosis were 61% less likely to die of cancer-specific causes than women who exercised less than three MET hours a week. And exercise was protective no matter the patient’s age, stage of cancer, or weight. Furthermore, patients benefited even if they hadn’t been physically active before their diagnosis.

• A third study, in the Journal of Clinical Oncology, found similar results after examining the effects of exercise on 832 men and women with stage III colon cancer.

How does exercise help fight cancer? Researchers theorize that exercise can regulate production of certain hormones that, unregulated, may spur tumor growth.