Does Exercise Fight Cancer?

Exercise may prevent some cancers, help cancer patients feel better, and be an important part of their treatment plan. Here's what you should know.

There was a time in the not too distant past when many doctors didn’t recommend exercise for cancer patients. Instead, they prescribed avoiding extra physical activity and rest. But that philosophy has changed. According to the National Cancer Institute (NCI), the field of exercise oncology — using exercise to help treat cancer and cancer therapy side effects — has grown and become an accepted part of cancer treatment for many patients.

Exercise helps cancer patients cope and boosts mood when their diagnosis and treatments cause anxiety and depression. In fact, the NCI recommends exercise to improve the quality of life for cancer patients and cancer survivors.

There’s growing evidence regular workouts might fight cancer directly, too, lowering the risk for malignancies and potentially reducing the rate of cancer recurrences.

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Cancer's connection with activity and inactivity

Not every cancer patient can exercise but, for those who can, physical exercise may play an important role in helping treat their disease. In fact, more than 1,000 randomized, controlled clinical trials in the field of exercise oncology, along with multiple epidemiological studies, have increased knowledge about the ways physically activity can help many cancer patients.

“We now have the evidence to tell us, with great confidence, that those living with and beyond cancer will benefit from being more physically active. We are at a point in the evolution of the field where we can dose exercise precisely, just as we do with drugs,” Penn State Cancer Institute exercise oncology researcher Kathryn Schmitz, PhD, explained in an NCI interview.

Physical activity appears to reduce the risk of certain cancers, especially colon and breast malignancies. Some of the strongest evidence indicates people who exercise regularly are 30 to 40 percent less likely to develop colon cancer, compared to sedentary folks.

Decreased activity, such as resting or sitting for long periods of time, can cause loss of body function, muscle weakness, and reduced range of motion.

What’s more, for people who have been treated for colon cancer, exercise may significantly reduce the odds their disease will recur, according to research by Dana-Farber and Harvard University scientists.

How may exercise prevent cancer?

Exactly how exercise may lower the risk for breast cancer isn’t known, but researchers are studying several possibilities. For example, some scientists think physical activity may prevent breast tumors from developing by lowering hormone levels, particularly in premenopausal women.

Regular exercise can reduce levels of insulin and insulin-like growth factor I (IGF-I). This might boost an immune response and stop cancer cells from growing. In addition, exercise helps keep weight under control. Excess body fat is known to be a risk factor for breast cancer.  

Brad Behnke, PhD, a professor of exercise physiology at Kansas State University’s Johnson Cancer Research Center, and colleagues are documenting how exercise may help treat certain kinds of cancers by increasing oxygen levels in the body.

Behnke hopes the research will reveal ways exercise can help directly fight cancer.

“Exercise is often prescribed to improve the side effects of cancer treatment, but what exercise is doing within the tumor itself is likely beneficial as well,” he said. “Exercise is a type of therapy that benefits multiple systems in the body and may permanently alter the environment within the tumor."

What you can do

Cancer patients should talk to their healthcare team about how much exercise, and what kind, is best for their particular diagnosis and the treatment that they are undergoing. The American College of Sports Medicine (ACSM), working with cancer experts from the NCI and other medical centers, developed guidelines to help cancer patients and their doctors develop effective, safe exercise and physical activity programs, for both those who are undergoing cancer treatment and those who have completed their therapies.  

“Our hope is that there will be more conversations about the need for formalized exercise programs for patients during and right after treatment programs that will be the cancer equivalent to cardiac rehab,” Schmitz said.

In general, Schmitz recommends that survivors of all cancers follow general public health recommendations for physical activity: 2 and 1/2 to 5 hours per week of moderate intensity activity, or 1 and 1/4 to 2 and 1/2 hours per week of vigorous activity. 

There’s no one-size-fits all exercise regimen for cancer patients and cancer survivors. “To prescribe a safe and effective exercise program, the patient’s age, type, and stage of cancer, treatment side effects, and other health considerations should be evaluated first,” Schmitz emphasized.

For more information, visit the ACSM’s Exercise Is Medicine website. It features the ACSM’s Moving Through Cancer initiative, which provides research findings about the benefits of exercise for cancer patients. The website also has an online directory to help healthcare providers, exercise professionals, and cancer patients find appropriate exercise advice and assessment.

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