Can exercise really cure cancer?

Forget bed rest. Increasingly exercise is being advocated as a wonder drug for all sorts of illnesses. And when it comes to cancer, a rigorous fitness regime could soon be a go-to prescription.

Ask Australian cancer scientist Professor Rob Newton about the role of exercise and he says it’s a gamechanger. “Pharmaceutical drugs target a particular problem, but then they cause all sorts of other side effects. Exercise doesn’t do that.”

Experts in the UK also recognize the benefits. The NHS is now prescribing weeks or months of intense exercise for newly-diagnosed cancer patients. It’s a move designed to rapidly increase fitness levels and prime the body to better deal with compromised immune systems that come from grueling cancer treatments.

Of course, having the physical fortitude to get through chemotherapy isn’t the only reason to get fit. Regular exercise strengthens mental wellness, which is critical for the seriously ill. Exercise can also help maintain a healthy weight, which is important as research links being overweight or obese with increased cancer risk – particularly for endometrial, esophageal, liver, pancreas and breast cancers. And new studies show exercise may even shrink tumors.

Exercise can make treatment more effective

A recent paper comparing physically active and inactive cancer patients has shown treatments aimed at tumor shrinkage are significantly more effective amongst those who exercise. Study participants who did 150 minutes of aerobic exercise, plus two sessions of strength training weekly for an average of five months (as they underwent four rounds of chemotherapy) enjoyed greater tumor shrinkage than those who didn't exercise. Growths shrank for 75 percent of the exercising group, compared with 37 percent of the non-exercisers. The exercisers also had a stronger immune response and lower levels of inflammatory chemicals in their blood.

Myokines: the exercise-induced molecules that torch cancer cells

Delving into the tumor-suppressive effects of exercise, another newly published study has honed in on the endocrine function of skeletal muscle. The study focused on myokines, a type of molecule that surges from muscle tissue during exercise. Scientists found that changes in myokine levels correlate to changes in lean mass, indicating that muscle hypertrophy is a key driver of serum myokine levels. After studying prostate cancer patients who completed 12 weeks of resistance and aerobic exercise, researchers observed significantly increased resting serum myokine levels. When this serum was applied to prostate cancer cells in a culture dish the researchers saw a 21 percent reduction of prostate cancer cell growth.

Is there an optimal exercise prescription?

According to an Exercise and Sports Science Australia report, there is no evidence-based set prescription suitable for all cancer patients. A mix of moderate to high-intensity exercise will be suitable for most, but any exercise prescription should be targeted according to patient- and cancer-specific considerations. And enjoyment is key. Any kind of activity that a patient considers enjoyable or perceives as positively influencing quality of life is endorsed. For example, while low-intensity yoga may not improve cardiovascular fitness to the same degree as other exercise modalities, the psychological benefits can be significant.

Professor Rob Newton, a co-author of the report, says it doesn’t matter what activity you do, as long as you do some physical activity each day. Even if you’re extremely unwell, you have to stay active. “With any chronic disease, injury, or illness, adopting a total rest strategy is counter-productive. If you adopt a rest attitude, it will only make your condition worse.”

To what degree can exercise curb cancer?

There is plenty of existing evidence linking prolonged sedentary behavior with an increased risk of some forms of cancer, in particular endometrial, colorectal, breast, and lung cancers. Now, a fascinating new study has highlighted exactly how significantly inactivity can spike cancer risk – and importantly, the study identifies what can be done to mitigate the risk. Comparing cancer incidence and the physical activity levels of almost 600,000 men and women, researchers strongly linked three percent of American cancers to inactivity. They concluded that over 46,000 cancer cases annually could be potentially avoided if the American population met the recommended five hours a week of moderate-intensity physical activity.

Learn more in our fascinating interview with cancer and exercise scientist Dr. Rob Newton.‍