What do you think when you hear the word cancer? A lot of us will think of a deadly disease treated by harsh chemicals and radiation. We then might wonder what caused it; was it smoking, too many x-rays, using the cell phone or something else? Rarely do we think it might be due to not getting enough exercise.

Even though we refer to all cancers like they are the same thing, they’re not. It’s really a group of diseases. There are certainly similar processes at the cell level but how a certain cancer progresses, how it can be treated and even prevented can differ based on where it is located.

When it comes to physical activity, we know the most about colon and breast cancers. Physical activity reduces the chances of getting both these cancers. For example, every four hours of walking per week or one hour of running, reduces the chances of getting breast cancer by 3%. And it doesn’t matter if the activity comes from planned exercise or activities like work or household chores. All activity is beneficial.

Physical activity can prevent other cancers as well. In a study of over 1.4 million people, physical activity reduced the chances of getting 13 out of 26 types of cancer. Interestingly, physical activity increased the chances of getting melanoma. Most likely because people exercise outside and have greater UV exposure (use of hats, UV protective clothing and sunscreen are easy ways to reduce that extra risk).

There are a number of ways in which physical activity can reduce the chances of getting cancer. One is through its effects on a number of hormones.

People who are active tend to have lower insulin levels and less chance of getting diabetes. High insulin levels may promote cancer development and progression by stimulating growth factors and DNA damage. Indeed, people with diabetes have an increased chance of getting cancer. For women, physical activity reduces estrogen levels in the blood. This is important because high estrogen may be associated with greater chances of breast cancer.

In addition, regular exercise reduces the amount of visceral adipose tissue (fat around the organs). This visceral adipose tissue is strongly associated with higher insulin levels and diabetes. So by being active, one’s insulin levels are further reduced.

It’s not just in prevention. Physical activity and exercise can help people recover from cancer and is often recommended to patients to help manage their fatigue following treatment. Chemotherapy and radiation therapy act by attacking cancer cells but also attack healthy cells. This results in a lack of energy and fatigue that can go on for weeks. Exercise can help reduce the fatigue regardless of cancer type. While it might seem counter intuitive to go exercising when one is tired, 10 min of exercise can provide an energy boost similar to a cup of coffee. Even exercising while undergoing chemotherapy can help reduce the negative effects the treatment can have on healthy muscle.

Up until recently, it was thought that exercise, and other lifestyle behaviours, had little to do with treating cancer. Once people got cancer, the patient was turned over to undergo chemo, radiation or surgery. The survival rates were quite low as well. Now, with the ability to identify cancer at early stages, and starting treatment early, people are living longer, which has provided the opportunity to see how exercise can help.

Long term studies tell us that being active after having cancer can reduce recurrence and early death. Some of the benefit is likely due to the same pathways as with preventing cancer, however, there are indications exercise is actually treating the cancer. Exercise has been shown to reduce cancer cell numbers in patients with colon cancer, and exercise in-hospital following colectomy surgery can speed up recovery time.

While many of these studies are small and it’s still early stages, it is clear exercise has a place in the treatment of cancer. This has led to official guidelines for physicians to recommend exercise to cancer patients.

With one in three people likely to get cancer during their lifetime, including a regular exercise routine in your life can help prevent and even minimize the effects of getting the disease.

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