The Roles of Exercise and Stress Management

The Physicians Committee

The Roles of Exercise and Stress Management

Healthy foods, physical activity, and reducing stress are increasingly recognized as vital ingredients of cancer prevention and survival. While genetics play a role in predisposing some people to cancer, other factors play a much greater role. In fact, much of what appears to "run in the family" results from shared exposure to environmental factors, such as cancer-promoting chemicals or dietary patterns.1,2 Many factors, including diet, physical activity, viral and bacterial infections, radiation, and exposure to carcinogens all influence one's risk of developing cancer.3,4

In the past two decades, a wealth of research has revealed that emotional factors and a lack of exercise can alter the body's resistance to cancer. Changing exercise patterns and how we handle “stress” could therefore play a powerful role in preventing or surviving the disease—a role no less important than making appropriate dietary changes. This page will tell you how to protect your body through stress management and exercise.

Immunity Against Cancer

Cancer begins with a major change in a normal, living cell. The transformation from a normal cell to a cancer cell is triggered by damage to the DNA, for example, by radiation or a carcinogenic chemical. These cells generally undergo cellular division more rapidly than the cells from which they originate. When a cancer cell divides, it forms two new cancer cells. The process continues until a mass of cells is created, called a tumor. The dangerous nature of cancer stems from the abnormal cells' ability to invade other tissues and travel through the blood and lymphatic vessels to other areas of the body, a process called metastasis.

Each of us is constantly exposed to carcinogens in our food, air, and water, resulting in the production of cancer cells within the body. Ordinarily, however, our immune system recognizes and destroys these cells before they have a chance to multiply. (The same thing happens to the vast majority of viruses and bacteria entering our bodies.) Given this fact, simply having abnormal cells develop is not the only factor in determining the course of cancer. The primary threat of cancer may result instead from the body's inability to eliminate the abnormal cells.

The immune system provides the body with a way to seek out and destroy cancer cells. Among the main anti-cancer components of this system are specialized white blood cells, known as T-lymphocytes (T-cells), which travel throughout the body to detect unusual cells. Some lymphocytes can produce various anti-cancer chemicals, such as tumor necrosis factor, interleukin, and interferon. These are the body's equivalent of chemotherapy, except they don't harm healthy cells.

The body's most immediate and powerful protection against cancer, however, results from the action of natural killer cells (NK cells), a specialized form of lymphocyte. NK cells descend directly on a microscopic tumor and begin devouring and disintegrating the tissue. As a consequence, many tumors never make it beyond the early stages.

Stress and Immunity

Stress affects us physically and psychologically. In the case of a perceived threat, the body undergoes a build-up of internal tension characterized by increased heart rate, blood pressure, and muscular tension, to prepare for swift and powerful action. In primitive times, these bodily changes probably helped us adapt to dangerous situations, such as sudden storms or attacks. In many cases, however, these aspects of the stress response are inappropriate in the context of modern society. You don't need tight muscles and a rapid heart rate, for example, when trying to resolve a business dispute or a conflict at home.

Under stressful circumstances, the brain signals the adrenal glands to produce corticosteroids, hormones which weaken the immune response. Corticosteroids exert such a powerful immune-suppressive effect that synthetic steroids (e.g., cortisone) are widely used as drugs to suppress immunity in allergic conditions and the rejection of transplanted organs. Cancerous processes, most notably breast cancer, are accelerated in the presence of large amounts of corticosteroids because they alter estrogen metabolism boosting an unfavorable hormonal response.5

Although the evidence is still evolving, emotional factors which influence stress may play some role in cancer resistance. Depression and helplessness, for example, may be detrimental to cancer prognosis and decrease quality of life.6-9 There seems to be a connection between stress and lowered immune function, particularly in T-cell and NK function. Long-term stress may be even more detrimental to cancer resistance, and emerging evidence suggests that certain cancers, such as breast and melanomas, may be more readily influenced by stress than others, especially early in their development.5,10

Managing stress and improving psychological well-being may not only decrease one’s risk of developing cancer, but improve chances for survival if cancer has been diagnosed.6 Improved immunity during cancer allows better recovery from difficult treatments and may decrease the incidence of complications, improving the patient’s overall health and well-being.

Findings from a large meta-analysis indicate that a lack of social support is associated with increased cancer incidence and mortality rates.11 Those who have a strong social support system have a 50 percent increased likelihood of survival.12 Knowing that there are others around to whom you can turn in tough times affords a sense of emotional stability, a context for dealing more effectively with feelings and the problems of life.

No scientific evidence has yet found that stress and emotions can directly cause cancer. The most plausible link is an indirect effect via the immune system. When immunity is weakened by stress, particularly in the presence of biological stressors such as a fatty diet or environmental pollution, then cancer can thrive and grow.

The Anti-Cancer Personality Is Hopeful and Expressive

In recent decades, a number of laboratory studies have provided evidence in support of the concept that stress-related factors can influence malignant disease. These studies have encouraged the use of therapeutic strategies for patients with cancer that rely on psychological and psychoneuro-immunological principles to accompany traditional medical treatments.13

Our responses to stress—or any life change—are individualized. What appears threatening to one person may seem harmless to another. How a person copes may be partly a function of age and experience.14 A study found that melanoma patients with the most "major life stress" in their backgrounds showed a greater will to confront and fight their cancer and less avoidance of the disease's frightening aspects.15 Those patients with less experience with major stresses tended to harbor a defeatist attitude and expected a poor prognosis. More recent studies help confirm these findings, where women with early life stressors and lack of social support were more prone to developing breast cancer, compared with those who tackled their stress and had more social support.5

When people feel that a major life upheaval is overwhelming or hopeless, their subsequent risk of cancer increases. A recent review of studies examining the link between personality and cancer survival determined that cancer patients who exhibit a high degree of neuroticism and low optimism tend to have a poorer chance of survival.16 Neuroticism generally describes an individual’s tendency toward worry and anxiety. This same review suggested that neurotic individuals also experience more stress and have a lower quality of life during treatment.16 For such individuals, and all cancer patients, managing stress may not only increase well-being but has the potential to improve health and survival.

Strengthening the Anti-Cancer Mind

Studies of various relaxation techniques suggest that the mind can enhance our immunity against cancer. In his book Psychological and Behavioral Treatments for Disorders Associated with the Immune System,17 Steven Locke, M.D., director of the Psychoimmunology Research Project at Harvard Medical School, describes more than 200 studies on the treatment of cancer by "mind/body" methods. Among the methods most often used by cancer patients are those which reduce anxiety, such as meditation relaxation techniques. A reduction in the anxiety, depression, and helplessness that often accompany the disease can make it easier to make decisions about treatment. Sharing one's fears and frustrations with a psychotherapist or members of a cancer support group can provide invaluable emotional stability and relief. Being around healthy and positive people is also important. Healthy children, with their playful, spontaneous nature, are particularly good companions in times of sickness.

Based on his extensive work with cancer patients, Bernie Siegel, M.D., notes that cancer survivors who enjoy a high quality of life tend to express their anger and other negative emotions freely, thereby avoiding a build-up of such emotions. He encourages friends and family members of cancer patients to help create positive expectations in the healing process.18

More recent research confirms that these approaches can be very valuable, as simple relaxation techniques such as yoga, art and music therapy, tai chi, and qigong (an ancient Chinese practice that aligns breath and movement) can be useful for dealing with the stress cancer brings.19

Meditation and Mindfulness

For most of us, developing the anti-cancer mind takes practice. Gentle techniques that require focused attention and tranquility such as meditation, qigong, tai chi, and many others may all help foster the mindset most conducive to health. Just as rest supports the immune system in times of stress, meditation and mindfulness practices may be effective ways of relaxing the body and strengthening its anti-cancer defenses.

One frequently used method, meditation, usually takes place in a sitting position with the eyes closed. The idea is not to suppress, analyze, or judge aspects of the psyche—even those that seem negative or disturbing. One simply notices the thoughts and feelings, then gently lets them go by returning to a particular focus (the breath, a candle, an image, a word, or sound). The purpose of the focus is to "anchor" the mind when it becomes too busy or distracted by thoughts, feelings, and sensations. In focusing on the breath, for example, one simply observes each inhalation and exhalation without trying to control them in any way. The restless chatter of the mind tends to diminish as one learns to attend to the focus.

Practicing this type of meditation for 15 or 20 minutes at a time (usually twice a day) results in a kind of awareness in which the mind is alertly attentive, yet tranquil. This "meditative mood" tends to carry over into daily experience, affording more clarity and flexibility in daily decisions and actions. The mind becomes more inclined to relax spontaneously in high-pressure situations. In many cases, one begins to enjoy the simpler pleasures in life, and attitude improves dramatically.

Meditation can also be applied directly to activities such as walking, knitting, or cooking. In each case, the individual gives total attention to the activity and, with practice, the meditative mood becomes second nature. As Joan Borysenko, Ph.D., former director of Boston's Mind/Body Clinic, writes in Minding the Body, Mending the Mind, "The final goal of meditation is to be constantly conscious of experience so that relaxation and peace of mind become the norm rather than the exception."20

There seems to be little doubt that meditation can be a helpful adjunct to any cancer treatment program, mainly by helping the meditator feel more at peace and more in control of cancer's stressful aspects. Studies suggest that meditation and other similar mind-body techniques may also help manage pain and the symptoms of cancer treatment, providing stress relief and an improved quality of life and outcome for the patient.21,22

Other mindfulness practices such as qigong may offer similar benefits to those experienced with other forms of meditation. In a 2012 study, researchers concluded that 81 cancer patients who engaged in 10 weeks of medical qigong not only experienced improvements in cognitive function and well-being, but also decreased an important marker of cellular inflammation known as C-reactive protein.23

Telomeres: How Mindfulness Works to Reduce Cancer Risk

In our bodies, stretches of DNA called telomeres protect our genes and make it possible for cells to divide. Telomeres are important because they relate to how we age and develop cancer. You may imagine telomeres as the plastic tips on shoelaces, because they work in a similar fashion, preventing chromosome ends from fraying and sticking to each other.

Each time cells go through normal division the telomeres get shorter. When they get too short, however, the cell can no longer divide and becomes inactive or dies. This process of telomere shortening is associated with aging, cancer, and a higher risk of death.

As we know, telomeres play an important role in genome protection. Studies try to identify how certain nutrients or exercise patterns can prevent telomere shortening. The Long Island Breast Cancer Study Project explored the relationship between the telomere length of white blood cell DNA and breast cancer risk, determining whether dietary intake of antioxidants would have any effect. In more than 1,000 women tested, a shorter telomere length was associated with a significant increased breast cancer risk. Women with lower intakes of β-carotene, vitamin C, and vitamin E all had shorter telomere lengths, compared with women who consumed more.24 Women who use exercise as a coping tool for stress have longer telomere lengths, compared with those who are not exercising.25

Research indicates that incorporating meditation or other mindfulness into your daily routine may help to slow telomere shortening. In recent studies where anxiety and stress were assessed, those with higher levels of anxiety were prone to greater telomere shortening.26,27 These simple interventions may reduce stress and increase hormonal factors that support telomere maintenance, which in turn may decrease cancer risk.28

Managing Stress

Reducing stress helps cut your risk of cancer and other health conditions, strengthens your immune system, and reduces anxiety. If you are relaxed, you are more likely to stick to a healthful lifestyle and less likely to depend on poor food choices that many people use to deal with stress.

Surefire Ways to Help Eliminate Stress:

  • Practice meditation, yoga, or tai chi. You can do this by attending classes or purchasing instructional DVDs.
  • Eat healthfully. Focus on antioxidant and fiber-rich foods like legumes, whole grains, fruits, and vegetables. Your mind and body will feel more focused and balanced.
  • Break a sweat. With regular exercise, your body will become a stress-fighting machine.
  • Learn time-management skills.
  • Set limits for yourself. Learn to say no to things that can add unwanted stress to your daily routine.
  • Enjoy yourself. Set aside time for hobbies and interests.
  • Catch enough Zzz's. Your body needs rest in order to recuperate from stress.
  • Say no to alcohol, drugs, and compulsive behaviors. These things provide only short-term relief and can be harmful to your health.
  • Spend time with loved ones and seek out other means of social support.
  • Learn to manage stress the healthful way. Make an appointment with a psychologist or other mental health professional trained in stress management.

Complementary and Alternative Medicine (CAM)

CAM does not have one definition. It consists of methods of medicine that are alternatives to common therapies in Western medicine. That is not to say they are “better” than traditional or conventional approaches, but that they can provide additional benefits to standard medical treatments. CAM can include acupuncture, spinal manipulation, meditation and/or prayer, herbal medicine, natural foods, supplements, aromatherapy, hydrotherapy, yoga, etc.

CAM modalities have been associated with improved NK cell function and immunity in some studies. For example, intake of green tea and some kinds of probiotics enhance NK cell activity. Administration of extracts from ginseng, aged garlic, Echinacea purpurea root, Chinese herbs, and some kinds of mushrooms significantly improve NK cytotoxicity (NK’s power to kill mutated cells) or restore NK cell activity in some immune-suppressive conditions.29 Some of these agents even show inhibition of metastasis (spread) of cancer. Moreover, acupuncture, skin rubdown, relaxation, massage therapy, music, laughter, and hypnotherapy enhance NK cell activity and/or NK cell numbers.29

One study showed practical improvements in immune function in cancer patients being treated with CAM: Cancer patients who were treated with CAM in conjunction with conventional treatments had an 18 percent decreased incidence of infection and a 13 percent drop in hospitalizations due to infection.30 Use of CAM during cancer treatment has also been associated with improved quality of life and decreased stress in cancer patients.31,32 Although it is important to discuss all forms of treatment with your doctor, incorporating CAM techniques into your treatment may offer some benefit to health and cancer resistance.

Exercise Against Cancer

The evidence that exercise may play an effective role against cancer is accumulating. Regular exercise has been associated with a reduced risk of cancers of the colon, breast, prostate, lung, and lining of the uterus (endometrium).33,34 A 2012 study published in the Lancet found that physical inactivity was responsible for 10 percent of colon and breast cancer diagnoses worldwide.35 The good news? Individuals have the ability to make informed decisions, alter lifestyles, and help fight cancer by using activity to their advantage. Let’s see what the research says and what type of exercise is best.

Exercise can contribute to cancer prevention and survival by improving immune system function. A position paper by the International Society for Exercise and Immunology shows that regular exercise may decrease the risk of developing cancer and also improve cancer survival after diagnosis. Physical actvity appears to increase NK cell activity while decreasing cellular inflammation, both very important factors in the development and progression of many cancers.36

But how much do we really need and for how long? Even a simple behavior such as walking may improve chances of cancer survival. A study published by the American Association for Cancer suggested that patients with prostate cancer could significantly improve their chances of survival by including regular walks in their lives. Researchers found that men who walked at a brisk pace for at least three hours per week had a 57 percent lower rate of cancer progression, compared with men who walked at a leisurely pace for less than three hours per week.37 Walking pace in particular seemed to be highly correlated with a decreased mortality risk, regardless of exercise duration.

The National Cancer Institute suggests that physical activity can have a similarly beneficial effect in women. A history of moderate, recreational exercise is associated with a reduced risk of breast and endometrial cancers.33 Recreational physical activity at any intensity reduces breast cancer risk in both pre and postmenopausal women.38 In the Harvard Nurses’ Health Study II, premenopausal women who were physically active had a 23 percent reduced risk of breast cancer, compared with those who exercised the least. The strongest evidence for prevention was seen in physically active women 12-22 years old. However, researchers concluded that exercising in both adolescence and adulthood may derive the most benefit.39

Numerous studies have assessed the effects of physical activity on endometrial cancer risk. Women who are physically active have a 20-40 percent reduced risk of developing endometrial cancer, and those who were most physically active experienced the greatest reduction in risk.40

For hormonally mediated cancers like breast and endometrial cancers, exercise may decrease the risk by changing body weight and metabolism of sex hormones, such as estrogen, which help to decrease cancer risk.33,34 For all cancer patients, regular exercise may help improve symptoms of physical and mental fatigue caused by cancer treatments, like chemotherapy. Typically, 90-120 minutes of moderate exercise weekly was enough to see improvements in fatigue, depression, and anxiety for women undergoing cancer treatment.41 A study review of 56 trials with more than 4,800 participants going through cancer treatment found significant improvements in their quality of life when exercise was included.42

Many cancer patients undergoing treatment have severe fatigue and depression. Being physically active can counter these negative effects and give patients more energy,43 which can be used to keep a healthy immune system and ward of cancer recurrence. However, for cancer survivors or those going through treatment, it is important to note that exercise regimens must be individualized. The type of cancer, degree of severity, and medications and treatments used will all help determine what exercise pattern is best. Therefore, one should exercise within the body’s needs and limitations because overexertion can result in immune dysfunction.44

A few words of caution should be added here. First, exercising every day will not cancel out the health-negating effects of emotional stress or a poor diet. All aspects of lifestyle should be considered as integral to the total picture of health. High-intensity exercise may be contraindicated for individuals whose immune function is already compromised, who are unwell, or who are at high risk of cardiovascular or other diseases. Most of the health benefits of exercise can be achieved with a moderate program designed with the individual’s specific needs in mind. Any decision to include exercise in the course of cancer therapy should take this into consideration. It is strongly advised that you check with your physician before beginning any exercise program, particularly if you are more than 40 years of age, are overweight, or have any pre-existing medical condition.

Use Your Body

Physical activity is great for your heart, your waistline, and your sense of well-being.

Our bodies are designed for physical activity: walking, dancing, biking, participating in games, and playing with children. These activities can get your heart moving and can burn calories. But we do them for fun, not to burn calories. The key is to remember what it was like to move your body—to enjoy a walk in the woods, a game of volleyball or touch football, or a night on the dance floor.

For starters, try something very simple. Just take a walk for a half hour per day or one hour three times per week. If you are feeling energetic, walk briskly. This is easy and gives you plenty of exercise. And, by all means, smell the roses along the way. Pick a place to walk that is enjoyable for you, with interesting sights, sounds, and smells.

If you prefer, pick any other activity. To give you an idea of how quickly your body can part with calories, here are some activities people enjoy and the number of calories they burn per hour for a 150-pound adult:

Activity Calories Burned Per Hour
Bicycling 400
Canoeing 180
Cooking 180
Dancing, ballroom 240
Gardening 480
Golf 345
Jumping rope 570
Ping-Pong 285
Playing piano 165
Racquetball 615
Swimming 525
Tennis, doubles 270
Tennis, singles 435
Volleyball 330
Walking, brisk 360

Fun is the key. And bring a friend along.

A word of caution: Do not push yourself too hard. If you are more than 40 or have any history of illness, medication use or joint problems, talk over your plans with your doctor before you begin.

The bottom line for men and women looking to prevent cancer or reduce the risk of a cancer recurrence. Get out there and move!


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