Exercise Is an Important Part of Cancer Prevention and Care

By Dr. Mercola

I first became aware of the relationship between exercise and cancer nearly 30 years ago but had no idea why it would impact cancer recovery. Initially I suspected decreased insulin resistance was the reason it worked.

However, after writing "Fat for Fuel," I recognized exercise actually is one of the most powerful signals for PGC 1-alpha, which is the primary signal for your mitochondria to reproduce and multiply, a process called mitochondrial biogenesis.

As I explain in my new book "Fat for Fuel," mitochondrial dysfunction seems to be at the foundational core of most all cancers, and anything that addresses that is likely to have a favorable impact on cancer.

While the featured documentary and studies reviewed in this article support the use of exercise to prevent and treat cancer, exercise pales in comparison to getting your body to burn fat as its primary fuel, using a ketogenic diet as described in my book "Fat for Fuel."

Documentary and Studies Confirm Benefits of Exercise for Cancer

The documentary "Exercise and Cancer," produced by the Australian Broadcasting Corporation's Catalyst television program, highlights the use of specific, targeted exercises for cancer patients receiving chemotherapy and radiation treatments at the Exercise Medicine Research Institute (Exercise Medicine) in Perth.

Professor Robert Newton, Exercise Medicine Research Institute co-director, suggests the idea for the use of exercise with cancer treatment stemmed from observations by oncologists that patients in their care often became too ill and weak to fight the disease.

In the interest of boosting energy, minimizing side effects and preventing further physical decline, Newton's guiding question became something to the effect of: "If we prescribed a tailored exercise program our patients could complete during their cancer treatment, would it make a difference?"

How Exercise Improves Cancer Treatment Outcomes

During the exercise trial highlighted in the documentary, doctors at Exercise Medicine marveled at how well their patients were doing. The 38 patients who exercised regularly seemed to be experiencing less of the usual side effects of chemotherapy — particularly less nausea and fatigue.

Not only were Exercise Medicine patients exercising on cancer-treatment days, but also three additional days a week. Based on results gleaned so far, Newton highlights the value of completing any exercise — even modest exercise — toward helping you beat cancer. He states:

"We now have a growing number of research studies showing that if people hit a certain level of physical activity, which is relatively modest … they'll more than double their chances of surviving cancer."

Exercising during cancer treatment also helped patients sustain muscle mass. The average cancer patient, Newton said, loses between 10 to 15 percent of their muscle mass, depending on the type and duration of their drug therapy.

Remarkably, patients participating in the exercise program reported little to no muscle loss; some even gained muscle mass. Says Newton:

"The benefit, in terms of muscle mass, is absolutely extraordinary, because we know there's no pharmaceutical intervention that can actually stop the decline in muscle mass. The only thing that will do it is highly targeted, prescribed, tailored exercise."

Exercise Should Be Part of Standard Cancer Care

Similar to Exercise Medicine, the U.K.'s Macmillan Cancer Support¹ has also made strong arguments for the inclusion of exercise in standard cancer care. They recommend moderate-intensity exercise for two and a half hours every week for anyone undergoing cancer care.

Just be sure to recover in between workout sessions. Exercise causes damage and adequate recovery is what actually provides the benefits.

Exercise is a vital part of nearly every cancer-treatment program. After all, exercise can help you overcome the most common side effects of conventional cancer treatment, having been shown to:

European Studies Underscore Value of Exercise for Cancer

Newton and his team found value in findings from two previous European studies focused on the merits of exercise in the treatment of cancer.

The first study,² published in 2013, was conducted in Sweden with a group of 10 healthy young men who exercised on a bike for 60 minutes at increasing intensity. Blood-serum samples were obtained from each participant before (rest serum) and after (exercise serum) the biking.

After incubating the exercise serum with prostate-cancer cells for 48 hours, researchers noted 9 of 10 samples suppressed cancer-cell growth. Incubating cancer cells with pooled exercise serum from all 10 samples for 96 hours resulted in a 31 percent inhibition of tumor cell growth compared to the rest serum. Newton calls the Sweden study "landmark:"

"[I]t's woken up the scientific community to say, 'There is something produced during exercise systemically.' The muscles are producing chemicals which are going to all parts of the body, and they're actually destroying tumor cells."

The second study³ was completed in Denmark in early 2016, involving two groups of mice with cancer. One group was given unlimited access to a running wheel, while the other group was not.

The experiment was repeated across groups of mice within five different tumor models, including liver and lung cancer, with the same results: Tumor incidence and growth in the exercise groups of mice was reduced by more than 60 percent as compared to the non-exercise groups.

When researchers cut into the tumor cells, they discovered tumors from the exercising mice contained countless natural killer (NK) cells that were actively working to destroy the cancer. They also noted epinephrine and interleukin 6 (IL-6) were released during exercise, which then triggered the release and effectiveness of the NK cells.

The study authors commented:⁴ "[T]hese results link exercise, epinephrine and IL-6 to NK cell mobilization and redistribution, and ultimately [the] control of tumor growth."

The Positive Effects of Exercise on Breast Cancer

Breast cancer patient Natalie Mathews, one of Exercise Medicine's trial participants featured in the documentary, agreed to the research institute's recommended exercise program without hesitation: "At the time, I wasn't very fit and healthy anyway, so why not try it," she said.

Mathews carried out her tailored exercise program at the hospital's in-house exercise clinic, either before or after her cancer treatments. She said initially her family wasn't sure exercise was a good idea but, like her, they came to recognize its many benefits:

"They didn't think I should do it. They were a bit scared because I looked so frail and … bald … But when they'd see me come home, still going, not lying on the couch and not having some of the symptoms typical patients get, I think they could see the benefit.

Believe it or not … [exercise] made me feel better. I felt better at the end of each session. I walked out with that extra bit of energy [and a] little bit less fatigue. The nausea was curbed, or kept at the same level."

A 2015 study⁵ published in the Journal of the National Cancer Institute showed aerobic exercise slowed breast-cancer tumor growth in mice, while making the cancer more sensitive to chemotherapy. Mark Dewhirst, professor of radiation oncology at Duke University School of Medicine and co-author of the study, has spent years figuring out how to increase oxygen flow to tumors with the goal of increasing the effectiveness of chemotherapy and radiation drugs:⁶

"We were truly amazed by these findings. I have spent the better part of the last 30 years trying to figure out how to eliminate hypoxia in tumors, and have looked at a lot of different approaches — drugs, hyperthermia and metabolic manipulations. None has worked very well, and in some cases, made things worse. So these findings with exercise are quite encouraging."

Oxygenating Your Tissues May Bolster Effectiveness of Chemo and Radiation

Based on the premise that aerobic exercise has been shown to increase the flow of oxygen-rich blood to tissues, Dewhirst and his team set out to formally test exercise as a means of altering tumor hypoxia. After surgically implanting mouse breast-cancer cells into female mice, researchers found the tumors to be slower growing in mice that had access to an exercise wheel as compared to mice who were sedentary.

Additionally, the density of small blood vessels feeding the tumors in the exercising mice was approximately 60 percent higher than that of the sedentary mice, making those tumors less hypoxic. Because chemotherapy and radiation work better when oxygen is present, such a result is noteworthy.

Based on the findings, exercise scientist Lee Jones, director of the cardio-oncology research program at Memorial Sloan Kettering Cancer Center in New York City and co-author of the study, validated exercise as a vital therapy for breast-cancer patients:⁷

"There is a growing body of work showing that exercise is a safe and tolerable therapy associated with improvements in many outcomes such as fitness, quality of life and reductions in symptoms such as fatigue in a number of cancer types, including breast cancer. On the basis of these findings in mice, we are now designing studies to test whether exercise can inhibit tumor growth and risk of recurrence in humans."

Regular Exercise May Boost Prostate Cancer Survival

Men diagnosed with prostate cancer can also benefit from exercise, according to a 2016 study⁸ by the American Cancer Society. The research, which included more than 10,000 men, aged 50 to 93, diagnosed between 1992 and 2011 with localized prostate cancer, revealed:

• Men achieving the highest levels of exercise prior to their diagnosis were 30 percent less likely to die than those achieving the least
• Men performing the highest levels of exercise after their diagnosis were 34 percent less likely to die than those performing the least

A 2014 Swedish study⁹ on the effects of exercise among men diagnosed with prostate cancer indicated men with active lifestyles achieved higher survival rates than those who were sedentary. "There is great potential for men diagnosed with prostate cancer to improve their own survival by being physically active," stated Stephanie Bonn, the study's lead author, of the Karolinska Institute in Stockholm.¹⁰

Bonn and her team analyzed data for 4,623 men from Sweden diagnosed with early-stage prostate cancer between 1997 and 2002, including details on each participant's physical activity levels and general health until 2012.¹¹ Men who biked or walked for at least 20 minutes a day after their diagnosis had a 39 percent decreased risk of dying from prostate cancer, compared to men who were less active. Moreover, daily exercise slashed the men's risk of dying from any cause by 30 percent.

Men receiving treatment for prostate cancer are often put on anti-androgen drugs, which causes them to become lethargic, gain weight and sometimes experience bone loss to the point of developing osteoporosis. Eight years ago, the Exercise Medicine team prescribed three types of exercise to a group of men on anti-androgen therapy.

One group did aerobic exercise only, another aerobic exercise plus resistance training and the third resistance work plus impact training. The impact work was composed of bounding, jumping and skipping. Notably, men in the third group maintained or improved their bone mineral density, while the others lost, on average, 3 percent over a six-month period. Newton said: "It was only the combination of resistance exercise and the impact loading that totally obliterated the bone loss."

Large Study Underscores Value of Exercise for Cutting Cancer Risk

A 2016 study,¹² presented in the Journal of the American Medical Association, associated exercise with a substantially lower cancer risk in 13 of the 26 cancers examined. The research involved a mega-pool of 1.44 million men and women from a dozen large European and U.S. prospective cohort studies (groups of participants who'd been followed for several years).

Participant age, body mass index, gender, self-reported data on exercise, smoking status and, if applicable, any cancer diagnoses, were analyzed to determine the effect exercise had on various cancers.

A total of 186,932 primary cancers were diagnosed during the follow-up period, which had a median length of 11 years. Regardless of the person's weight or smoking history, the data suggested physical activity cut their risk of cancer. For example, exercise slashed the risk of kidney cancer by 23 percent, lung cancer by 26 percent, liver cancer by 27 percent and esophageal adenocarcinoma by 42 percent.

Regular Exercise Also Reduces Risk of Cancer Recurrence

Evidence supporting exercise as a means to reduce your risk of cancer recurrence is quite impressive. For example, previous research has shown that breast- and colon-cancer patients who exercise regularly have half the recurrence rate of non-exercisers.¹³ According to Ciaran Devane, chief executive of Macmillan Cancer Support:¹⁴

"Cancer patients would be shocked if they knew just how much of a benefit physical activity could have on their recovery and long-term health, in some cases reducing their chances of having to go through the grueling ordeal of treatment all over again. It doesn't need to be anything too strenuous — doing the gardening, going for a brisk walk or a swim, all count."

Denmark study co-author Pernille Højman, a researcher at Copenhagen's Center for Physical Activity Research, suggests:¹⁵  

"Many studies have shown quality of life is improved by exercise. For example, we know from population studies that cancer patients who are declared healthy, have a better survival rate when they exercise."

If you're undergoing cancer treatment and are considering taking up exercise for the first time, it's advisable that you consult with your physician first. You may also want to seek out the advice of an exercise physiologist. Rather than a personal trainer, you will need an exercise physiologist who works with cancer patients and survivors.

An exercise physiologist will know about cancer drugs and the types of treatment you are undergoing. That way, the exercise program can be tailored to your specific needs with respect to your particular type of cancer.  With a final word, Newton underscores the value of and need for exercise as part of standard cancer treatment:

"The evidence [for exercise] is so strong now, and cancer patients deserve this medicine. It's a very powerful medicine. It actually increases their survival and has no side effects. So, what we need now is … medical and health professionals to embrace it and make it an integral component of the overall management of the cancer patient."