When we hear the word cancer, most of us think of a deadly disease treated by harsh chemicals and radiation. We might wonder what caused it; was it smoking, too many x-rays, using the cell phone, genetics or something else? Rarely do we think it might be due to not getting enough exercise but targeting cancer with exercise can both prevent and treat the disease.
Cancer occurs when cells in the body no longer follow the normal process of growth and development. This may include cells continually multiplying, growing uncontrollably and moving to other areas of the body (metastasis). Even though we refer to all cancers like they’re 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’s located.
Preventing Cancer with Exercise
When it comes to cancer and exercise, 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.
Exercise 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 (skin cancer). 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). And men at higher fitness levels have less chances for getting, and dying from, colon, prostate and lung cancer.
There are a number of ways in which exercise can reduce the chances of getting cancer. People who are active tend to have lower insulin levels. This is likely beneficial as 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. Regular activity is also associated with improved immune function, and immune cells are key to identifying and destroying cancerous cells.
Treating Cancer with Exercise
It’s not just prevention. Physical activity and exercise can help people recover from cancer. Up until recently, it was thought exercise and activity had little to do with treating cancer. Once people got cancer, they underwent chemotherapy, radiation or surgery. The survival rates were quite low. 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.
Exercise is often recommended to patients to 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. And exercising while undergoing chemotherapy can reduce the negative effects the treatment can have on muscles and the nervous system.
In the long-term, being active can also reduce your chances for complications after a cancer diagnosis. Women with breast cancer who met (or exceeded) the physical activity guidelines (20-30 minutes of moderate/vigorous activity on most days) before and after diagnosis, were 55% less likely to have a recurrence and 68% less likely for early death compared to inactive women. And exercising after can also reduce recurrence and early death in those with prostate and colon cancer.
The Effects of Exercise on Tumor Growth
Some of the benefits of exercise are likely due to the same pathways as with preventing cancer such as strengthening the immune system. There are also indications exercise can actually treat the cancer. In mice, exercise has been shown to activate genes known to suppress tumor growth. And another study in mice found just that—exercise does suppress tumor growth. This was likely due to an improved immune system in recognizing tumors in the exercising mice.
Fewer studies have been conducted in people, but these also indicate direct effects of exercise on tumor growth. In one study, blood was taken from men with prostate cancer before and after a 12-week exercise program (resistance and aerobic training). The blood taken after the exercise program was effective in reducing prostate cancer cell growth in a lab. Exercise has also been shown to reduce cancer cell numbers in patients with colon cancer.
While many of these studies on the effect of exercise on tumor growth are small, it’s still early stages. However, it’s 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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This post was originally published on April 17, 2019 and updated on July 19, 2023.
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