Exercise and Cancer 101: Why You Should Just Do It!

Why is exercise so important:

• Exercise reduces your risk of developing cancer.
• Exercise during and after cancer treatment may reduce your risk of cancer recurrence and progression.
• Exercise improves quality of life in cancer patients and survivors.

 

Physical Activity Guidelines:

The American Cancer Society, the American College of Sports Medicine, the American Institute for Cancer Research, the U.S. Department of Health & Human Services and others recommend that all adults should do:

• at least 150 minutes per week of moderate-intensity aerobic activity (e.g. brisk walking.)
• at least 2-3 sessions of strength training per week (e.g. weights, resistance exercises) that include exercises for major muscle groups
• stretch major muscle groups and tendons on days that other exercises are performed

New research indicates that walking for 15 minutes (10-15 minutes after meals) three times per day is healthier than doing a single 45 minute walk. It appears that walking after meals significantly reduces the blood sugar surge that occurs after eating. The most important time to walk after a meal was after eating dinner.

What If I Can’t Reach These Goals?

If you are not able to meet these goals for health reasons, don’t be too hard on yourself. Try to be as physically active as your abilities and conditions allow. Even a modest amount of physical activity is better than none.

• Physical inactivity has been shown to lead to early death from cancer, heart disease, diabetes and other chronic conditions.
• Did you know that physical inactivity actually kills as many people as smoking?  Physical inactivity was responsible for 5.3 million out of 57 million deaths throughout the world in 2008, which is comparable to the effects of smoking.

 

Get moving! New research now indicates that the amount of time you sit each day (even if you are regularly physically active and not overweight) is associated with physiologic changes (e.g. insulin resistance and inflammation) that increase your risk of cancer and other chronic conditions, and dying early from any cause. The longer you sit, the greater your risk. The researchers found that by sitting 6 or more hours a day increased the risk of early death from all causes by an average of 35% for women and 18% for men, even if they exercised (compared to those who sat less than 3 hours a day.)

Failing to exercise plus sitting for 6 hours or more a day proved even more hazardous. The combination of little physical activity and long periods of sitting was linked to a 94% higher risk of premature death for women and a 48% higher risk for men compared with those who sat the least and exercised the most!

Fortunately, they discovered that by simply taking activity breaks (e.g. getting up and walking around) for as little as one-minute is able to reduce these risks.

If you are a cancer survivor, your sedentary time increases your risk of becoming overweight and developing or exacerbating other chronic condition such as diabetes and cardiovascular disease.

• Some patients (e.g. those with head and neck or gastrointestinal cancers) may lose a significant amount of muscle mass during or after their cancer treatment, so much so that it can be difficult for them to get up out of a chair. In this group, exercises that help build muscle are important.
• Other patients (e.g. those with breast or prostate cancer) may gain a significant amount of fat as a result of the systemic treatments they often receive.  In this group, exercises that help patients lose fat and get back to a healthful body mass index (BMI) are important.

 

The American Institute for Cancer Research (AICR) spokesperson, Alice Bender, MS RD, says “So this person, who fits the traditional definition of someone who’s physically active, is actually active just 3 percent of his waking day…By thinking in terms of break time, however, Americans can infuse the remaining 97 percent of their day with short periods of activity that can protect against many cancers.”

**I love this AICR infographic to help explain the association of sedentary hours and cancer risk**

 

Should I Exercise During Cancer Treatment?

Absolutely! Exercise during cancer treatment is not only safe and feasible, but also beneficial for reducing fatigue, improving physical function, and enhancing overall well being. Studies show that exercise during cancer treatment reduces the occurrence of negative, post-treatment outcomes, including loss of bone density and muscle mass, cardiovascular performance, etc.

It’s important to keep in mind that exercise programs may need to be adapted depending on your health status and medical treatments you may have received (e.g. radiation therapy, surgery, hormonal therapy.)

Low-intensity exercise programs, including walking, stretching and yoga are best suited for individuals who were sedentary prior to their cancer diagnosis. Individuals who are on bed rest can benefit greatly from physical therapy, which maintains strength and range of motion while also counteracting the effects of depression and fatigue.

**Read our article on the benefits of Yoga**

 

To better address these issues, a panel of 13 researchers with expertise in cancer, fitness, obesity, and exercise training published (July 2010) guidelines for people who have been diagnosed with cancer, American College of Sports Medicine Roundtable on Exercise Guidelines for Cancer Survivors. In April 2012, the American Cancer Society published their updated guidelines, Nutrition and physical activity guidelines for cancer survivors.

 

The experts conclude:

• Although there are specific risks associated with cancer treatments that need to be considered when survivors exercise, there is strong evidence that exercise is safe during and after cancer treatment.
• Exercise training-induced improvements can be expected concerning aerobic fitness, muscular strength, quality of life, and fatigue in cancer survivors.
• Resistance training can be performed safely by breast cancer survivors with and at risk for lymphedema.

 

Need Some Motivation to “Just Do It”? 

Physical Activity Reduces the Risk of Developing Cancer:

Did you know that physical inactivity contributes to the development of 49,000 cases of breast cancer and 43,000 cases of colon cancer occurring in the U.S. every year…and that’s just for breast and colon cancers. One out of every ten cancer diagnoses are linked to inactivity.

30 minutes of walking, 5-days per week is all it takes to reduce your risk of cancer (for example):

• breast and colon cancers: 25 to 30 percent reduction in risk
• prostate cancer: 10 to 20 percent reduction in risk
• endometrial cancer: 30 to 35 percent reduction in risk

 

Physical Activity Reduces the Risk of Cancer Progression, Recurrence and Death:

To be clear, the data do not definitively prove that physical activity improves survival from cancer. That said, the evidence is quite convincing, particularly for breast, prostate and colon  and ovarian cancers.

• Breast cancer:  breast cancer survivors who reported doing more than 8 hours each week of moderate-intensity exercise (walking was most common) had a 26-40% lower risk of death, breast cancer death, and breast cancer recurrence compared with the survivors who reported doing less than 1 hour each week.
• Prostate cancer: prostate cancer survivors who exercised more than 3 hours per week had a 33% lower risk of death from any cause and a 35% lower risk of dying from prostate cancer. Both nonvigorous activity and vigorous activity were associated with lower all-cause mortality. Only vigorous activity was associated with reduced prostate cancer mortality, with a suggestion of a reduced risk for longer duration of brisk walking. Prostate cancer survivors who undertook vigorous physical activity for 3 hours per week or more were found to have a 49% lower risk for all-cause mortality and a 61% lower risk for prostate-cancer-specific mortality than those who exercised for less than 1 hour per week. Men who reported a brisk walking pace (greater than 3 mph), compared with an easy walking pace (less than 2 mph), had a 48% lower risk for prostate cancer progression. Researchers note that the walking pace was associated with a decreased risk for cancer progression.
• Colon cancer: colon cancer survivors treated with surgery and adjuvant chemotherapy who engaged in more than 6 hours of moderate-intensity walking per week had a 47% improvement in recurrence free survival (lower cancer recurrence and cancer-related death), compared with inactive patients.
• Ovarian cancer: ovarian cancer survival was 31% higher for women who reported greater than 2 hours of activity per week as compared to those reporting less than one hour per week.

 

How Does Physical Inactivity Promote Cancer?

Researchers are not exactly certain as to the precise mechanisms linking cancer with physical inactivity, but the picture is becoming more clearer.

What we do know is that physical inactivity effects crucial biological factors of cancer development, progression and recurrence: sex hormone levels, insulin resistance, inflammation and obesity.

• Sex hormone levels: excess estrogen can stimulate the growth of numerous cancers (e.g. breast, uterine, ovary.) Estrogen is produced predominantly by the ovaries, prior to menopause. However, fat tissue can also produce estrogen. The more fat tissue you have, the more estrogen your body makes.
• Insulin resistance: insulin is a hormone that is responsible for enabling your cells to transport and use sugar for energy. If your cells become less responsive to insulin (which occurs mainly as a result of obesity, stress, inflammation), blood sugar levels rise and more insulin is secreted by your pancreas to help compensate. Insulin (and a similar hormone produced along with insulin called, “insulin-like growth factor 1”, or “IGF-1”) and IGF-1 are cancer growth factors, which stimulate the growth and progression of cancer cells. Furthermore, cancer cells love sugar. So, the more resistant your tissues are to insulin, the more blood sugar is available for your cancers cells to consume. Read more about cancer and sugar in our Cancer, Sugar and Carbohydrates 101 article.
• Inflammation: promotes the development and progression of many cancers. Fat cells produce inflammatory hormones called, cytokines, which are responsible for stimulating cell growth, replication and suppressing cell death. These cytokines signal your body to increase the production of inflammatory cells (e.g. macrophages and neutrophils), which release DNA-damaging free radicals chemicals. If sufficient damage occurs to a cells’ DNA, cancer-causing mutations may arise. Inflammatory cytokines are involved in causing insulin resistance (see above) and stimulating the production of stress hormones (e.g. cortisol). Read more about the association of stress, stress hormones and cancer in our Stress and Cancer 101 article.
• Obesity: involved in each of the 3 topics above. Obesity can also lead to further inactivity due to physical limitations.

One of my favorite review articles on this subject is from, “Mechanisms linking physical activity with cancer” (by Anne McTiernan, M.D., Ph.D.) The figures below are from this Nature Reviews publication.

 

Additionally, other anti-cancer effects of exercise include:

• Increased the expression of tumor suppression genes and DNA repair genes
• Reduced tumor stimulation and growth
• Reduced free radical production
• Strengthened immune system

Other Important Benefits of Physical Activity (not directly related to cancer): 

• Reduced fatigue (in fact, exercise is one of the only proven modalities that consistently has been shown to reduce fatigue after cancer treatment)
• Improved sleep function
• Improved overall quality of life
• Improved muscle strength and flexibility
• Improve bone density
• Improved cardiovascular performance
• Improved immune function
• Reduced stress (read our Stress and Cancer 101 article to learn more)
• Improved mood; reduced anxiety and depression

 

Just to really drive the point home, here are 2 recently published comprehensive review articles reporting on the efficacy of exercise in improving quality of life during & after cancer treatment:

• Exercise interventions on health-related quality of life for cancer survivors
• Exercise interventions on health-related quality of life for people with cancer during active treatment

 

So, I’ve Convinced You To Get Active…Now What? 

The American Cancer Society reports data that, depending on the cancer site, only 53-70% of survivors met minimum physical activity recommendations. If you are in this group of survivors who want to start getting more physically active, I’d recommend you begin by looking for a fitness trainer to help you get started.

When selecting a fitness trainer, it’s strongly encouraged that you to find one who is knowledgeable and experienced in working with individuals who have been diagnosed with cancer. Your trainer needs to be made aware of the specifics of your cancer diagnosis and treatment so that they can make informed, safe choices about exercise testing and your regimen.

• Your specific cancer and treatment can affect numerous body systems that are required for and affected by exercise training, including the neurologic, musculoskeletal, immune, endocrine, metabolic, cardiopulmonary, and gastrointestinal systems.
• Because cancer treatments are customized to each person, I recommend that you ask your fitness trainer to contact the cancer care team for more precise information regarding your health and the treatments you received. You may not know the details that your fitness trainer needs to help them better understand the health limitations you may have (e.g. restrictions, complications, side effects, etc.) For example, men who have taken hormonal therapy for prostate cancer are at a greater risk of fractures and women who have had breast cancer surgeries may have shoulder range of motion limitations. Your trainer will design an exercise regimen that will take these and other factors into account.

 

Finding Experienced Trainers:

• The American College of Sports Medicine (ACSM) in collaboration with the American Cancer Society (ACS) has developed a specialty certification (ACSM/ACS Certified Cancer Exercise Trainer or CET) for fitness professionals working with clients who have been cleared by their physician for independent exercise and physical activity. Find a ACSM/ACS CET certified trainer.
• The Lance Armstrong Foundation has partnered with the YMCA to help train fitness staff at YMCAs across the country to work with and meet the needs of cancer survivors. LIVESTRONG at the YMCA is a twelve-week, small group program designed for adult cancer survivors. The goals of this program are to:  help participants build muscle mass and muscle strength, increase flexibility, endurance, improve functional ability, reducing the severity of therapy side effects, preventing unwanted weight changes and improving energy levels and self esteem. Find a LIVESTRONG at the YMCA program near you.
• The Rocky Mountain Cancer Rehabilitation Institute (RMCRI) is the only facility of its kind in the country and is recognized as a frontrunner in cancer rehabilitation. They have provided clinical rehabilitation services to over 1000 adult patients with all types of cancer in various stages of treatment and with increasing severity of illness. In addition to providing rehabilitation services to patients, they are actively involved in academic research and training (more than 500 undergraduate students trained as cancer exercise specialists and 215 master’s and doctoral graduate students mentored to conduct clinical and basic research in cancer rehabilitation.)
• Many cancer centers also have fitness & rehabilitation programs that are available to you.

 

http://youtu.be/aJhC2DPBeyw

http://vimeo.com/44480344

 

Are There Specific Exercises That Are Recommended?

Any and all movement is positive! Contemporary society is largely sedentary; we log long hours sitting on our daily commutes, sitting in office chairs, and then sitting at home in front of the television. In order to enjoy the cancer reduction benefits of exercise, you will need to proactively incorporate physical activity into your daily schedule. Exercise is not limited to a gym workout. Taking the stairs at work, parking at the back of the parking lot rather than the front, biking or walking to work, taking a yoga class, or going for an evening walk through the neighborhood are all easy ways to get active. Aim for a mix of cardio activities, core exercises, and strength training each week.

Examples of moderate exercise include walking at a brisk pace (3 to 4.5 mph), bicycling on level terrain, yoga, doubles tennis, golf and recreational swimming. Examples of vigorous activity includes jogging or running, high-impact aerobics, bicycling up steep terrain, circuit weight training, singles tennis, swimming paced laps.

**Read our article on the benefits of Yoga**

 

Precautions:

**From the American Cancer Society’s April 2012 publication, Nutrition and physical activity guidelines for cancer survivors**

“Despite the many benefits of exercise for cancer survivors, particular issues may affect the ability of survivors to exercise. Effects of treatment may also increase the risk of exercise-related injuries and adverse effects, and therefore specific precautions may be advisable, including:

• Survivors with severe anemia should delay exercise, other than activities of daily living, until the anemia is improved.
• Survivors with compromised immune function should avoid public gyms and public pools until their white blood cell counts return to safe levels. Survivors who have completed a bone marrow transplant are usually advised to avoid such exposures for one year after transplantation.
• Survivors experiencing severe fatigue from their therapy may not feel up to an exercise program, and therefore they may be encouraged to do 10 minutes of light exercises daily.
• Survivors undergoing radiation should avoid chlorine exposure to irradiated skin (eg, from swimming pools).
• Survivors with indwelling catheters or feeding tubes should be cautious or avoid pool, lake, or ocean water or other microbial exposures that may result in infections, as well as resistance training of muscles in the area of the catheter to avoid dislodgment.
• Survivors with multiple or uncontrolled comorbidities need to consider modifications to their exercise program in consultation with their physicians.
• Survivors with significant peripheral neuropathies or ataxia may have a reduced ability to use the affected limbs because of weakness or loss of balance. They may do better with a stationary reclining bicycle, for example, than walking on a treadmill.”

 

Additional precautions and recommendations:

• “Exercise During Cancer Treatment“, January 2012 (by Kerry Courneya, Ph.D., and Margaret McNeely, Ph.D.)