Healing Through Exercise: Scientifically Proven Ways to Prevent and Overcome Illness and Lengthen Your Life (18 page)

Finally, the risk for prostate cancer is also reduced by physical exercise. In the United States it is one the most prevalent cancers among men, whereas it is far rarer among men living in Asian countries. However, as men from Japan or China immigrate to the United States and adopt the Western lifestyle, their prostate cancer risk approaches that of American men. Apart from diet, lack of exercise plays a major role influencing the risk for prostate cancer by 10 to 70 percent.

But how can an active life stave off cancer? As with colon cancer, there appears to be a link to digestion. In sedentary bodies the peristalsis of the colon is slowed down. Thus, cancer-causing agents in the food stay for an extended time in the colon. The researchers have also identified numerous other factors that help to prevent tumor growth.
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BODY FAT AND DANGEROUS HORMONE LEVELS

Physical activity reduces weight and thus the production of female sex hormones, especially estrogens because these are made not only in the ovaries but also in the fat tissue. That is why lack of exercise often leads to both fat deposits and elevated hormone levels, which can promote the growth of tumors in the cervix, endometrium, ovaries, and breast.

The most natural way to reduce the level of these hormones is physical activity. Anne McTiernan of the Fred Hutchinson Cancer Research Center has demonstrated this in a trial of 267 women who did not take artificial hormones.
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Researchers weighed the women, noted their weekly amount of exercise, and assessed their levels of the hormones estradiol and estrone. These hormones are very active and can promote breast cancer.

The result: women who are heavy and hardly move have hormone levels exceeding those of active and normal-weight women by 50 to 100 percent. So by watching their weight and performing some moderate exercise, women can reduce hormone levels under their own steam to a “healthy level,” concludes McTiernan.
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According to her study, 30 minutes of moderate training, five days per week, is sufficient. The exercise appears to increase the level of certain proteins that in turn can remove excess hormone levels from the blood.
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Furthermore, it beneficially influences the pathways that are involved in the production of hormones. In physically fit bodies there is a high level of certain intermediate products that cannot be converted into hormones. By comparison, in overweight women there is a high level of products than can be turned into hormones. In addition, exercise seems to be connected with an advantageous composition of the breast tissue. A trial in Norway showed that women who get at least two hours of activity per week have less dense breast tissue than sedentary women. And the higher the tissue density, the higher the breast cancer risk.
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The cancer-causing potential of these hormones is widely known and acknowledged in medical research. All the more odd, then, that pharmaceutical companies manufacture estrogen products and still, despite large studies showing risk, sell them as “hormone replacement therapy” (HRT) to menopausal women. In the United States, a large trial of 16,000 women had to be terminated as the emerging data from it revealed that the hormone products do more harm than good: If 10,000 women take the products estrogen and progestogen for one year, eight more of them will develop breast cancer than those who do not take them. Even though these pills were also touted as preventive against heart disease, they were also cardiovascular dangers. What miserable credentials for a product that is claimed to be a remedy.
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Women who take hormone pills face a higher risk of cancer, for two possible reasons. As mentioned, estrogens can trigger the growth of cells in the breast tissue. Moreover, hormone consumption affects behavior and dampens the desire to exercise. Studies with mice suggest a direct link. The more estrogens given to female mice, the less distance they ran on a treadmill.
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Because of the wide publicity given the large trial that had to be stopped, many fewer women are taking pills. Many of the benefits supposedly offered by the replacement hormones, such as a more youthful appearance or a healthier heart, are more easily found on a hike or at a gym.

EXERCISE AS CANCER PREVENTION

People who exercise also influence their immune system, and thereby their cancer risk. But the effect of exercise can go both ways. An overload can weaken the immune system and even promote the growth of a tumor. On the other hand, the right dose of exercise does strengthen the immune system and can hinder or inhibit tumor growth. Moderate exercise appears to promote the production of certain cells of the immune system. Cytotoxic T cells, natural killer cells, and similar cells patrol the body and are capable of destroying tumor cells. The members of the beneficial platoon of cells have been shown to be produced in bigger numbers by “regular, moderate exercise.”
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Mice allowed to run as much as they want, on running wheels, boost their production of natural killer cells. They then have significant advantages compared to sedentary mice because their immune systems can fight more cancer cells, and fewer tumors grow.

With age, the immune system becomes weaker, and physicians suspect this decline is one of the reasons cancer risk increases with age. The aging process can be clearly seen in T cells. Their number dwindles in the course of the years, and their ability to detect and fight foreign cells becomes weaker. However, this decline can be halted and reversed: Elderly women and men were shown to improve the function of their T cells by exercise compared with sedentary controls of the same age.
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This finding points to an additional mechanism that underlies the cancer-fighting potential of exercise: it counteracts the age-related decline of the immune system.

Another support for the cancer-preventing effects of exercise can be found in studies of diabetes. Insulin produced in the pancreas is needed by cells so that they can absorb glucose from the blood and store it. The level of insulin must correspond to the body’s needs, and if this balance is destroyed, the likelihood for developing cancer increases.

Patients suffering from type 2 diabetes have been found to produce higher quantities of a protein called insulin-like growth factor I (IGF-I), which is thought to trigger cancerous growth. The rates of colon, liver, pancreas, endometrium, and breast cancer are in fact higher among people with type 2 diabetes.
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That does not sound good at all, but luckily one can do something about it: Physical exercise, as we saw, can reverse the symptoms of diabetes and also appears to lower the IGF-I level.

BMI AND CANCER

As they continue to explore the causes of cancer, doctors ascribe a greater role to obesity than they once did. British scientists reviewing data pooled from more than 140 studies have just confirmed that the risk of developing a number of common and some less common cancers goes up with increasing BMI.
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An earlier study had already revealed that the risk of obese men for developing an extraordinarily aggressive version of prostate cancer is increased by 80 percent.
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Thomas Hawighorst and Günter Emons, at the University Hospital Göttingen, Germany, published a review article on the subject painting a very somber but realistic picture. By now, there is “sufficiently hard evidence for the connection between adiposity and an elevated risk for cancer” of the endometrium, the kidney, the breast, the colon, and esophagus, whereas, “The prognosis for adipose women with breast cancer is worse, and gaining weight after the diagnosis also has a bad prognostic effect.”
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The American Cancer Society published a particularly extensive survey on the subject.
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The study started more than 20 years ago and included more than 900,000 women and men. Their average age was 57, and none had any tumor-based diseases. In the following 16 years, 6.3 percent of them died because of a condition that was caused by cancer. Then, the researchers analyzed the data to see whether there was a link between the death rate and body weight. In order not to distort their findings, they excluded risk factors and used only data from people who never had smoked.

According to the study, the risk for dying from cancer is approximately 10 percent higher for women with a BMI between 25 and 29.9 and three times higher for women with a BMI between 30 to 40. And extremely obese women have a risk for dying from cancer that is elevated by 88 percent, compared to normal-weight women. The data of the men revealed a similarly gloomy picture.

In total, the researchers figure that obesity causes about 20 percent of all deaths of women related to cancer. Among men, the number is about 14 percent. The experts of the International Agency for Research on Cancer in Lyon, France, estimate that 25 percent of cancer cases worldwide are caused by excess weight or obesity and a sedentary lifestyle.
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Apart from overeating, lack of exercise is in most cases the reason why people balloon and develop a pathological condition. Excess fat on the body impairs the whole metabolism and causes several of the risks mentioned earlier. The biochemistry of the estrogens becomes messed up, and the insulin system gets out of balance. The longer an affected person remains physically inactive, the worse everything gets—because muscle mass is incrementally replaced with fat.

Love handles and potbellies are by no means passive additions to a body; rather, they actively interfere with some processes in the rest of the organism. Certain messenger substances, so called adipocytokines, are produced by fat tissue and can play a role in the development of cancer. The experts Hawighorst and Emons conclude that in obese people “the metabolic-biochemical effects of overweight can cause the formation of a malignant tumor in a multi-level process.”
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Researchers still speculate whether and if exercise affects an already existing tumor. Physical activity increases the demand for oxygen and nutrients—which might starve the tumor of these resources. If the blood is primarily pumped into the muscles, one could reason that there is not much left to feed the tumor.

Although evidence continues to accumulate that being physically active reduces a person’s risk for developing certain cancers, to date, the many details of the mechanism remain unknown. Many factors may act together and might vary from individual to individual. However, even though the ideal amount of exercise to prevent cancer has yet to be determined, doctors and physiologists working in the field are convinced that becoming active is worthwhile anyhow. As Kim Westerlind of the AMC Cancer Research Center in Denver, Colorado, concludes, “It would appear reasonable to suggest that regular moderate physical activity be incorporated into [a] healthy lifestyle for all its already well-established benefits, as well as to potentially reduce cancer risk.”
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EXERCISE AND QUALITY OF LIFE IN CANCER PATIENTS

The doctrines of few medical fields have been as drastically turned around as they have in cancer medicine. Generations of doctors had been taught that people diagnosed with cancer primarily needed rest. Patients were discouraged from exercising, out of the erroneous belief that this would worsen their health. When the physician Klaus Schüle established the world’s first training group for cancer patients in Cologne, Germany, many of his colleagues were outraged. A radiologist warned him: “Can you guarantee you are not going to trigger metastases?” Schüle replied: “Can you guarantee that your rays don’t trigger growth of new tumors?”
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By rejecting exercise for their cancer patients, medical doctors did more harm than good, says Fernando Dimeo of the Hospital Charité in Berlin. “During chemotherapy and the weeks and months to follow patients were put in a passive role. Doctors were afraid of overburdening them and advised many of the patients not to participate in sports and demanding activity even in the long term.”
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But recommending cancer patients to take it easy has severe consequences. At first, people are shocked to learn they have cancer. Then, they are told not to use their bodies much any longer—which makes the situation even more devastating because they now feel completely at the mercy of their illness. On top of this, being confined to rest worsens the impact of chemotherapy and of the cancer drugs, which can cause anemia and heart problems and loss of strength as well as vitality. As a result they are tired, and they become short of breath. “These symptoms can be worsened by lack of exercise and the subsequent loss of endurance,” warns Dimeo.

In no time the patient is caught in a vicious circle of declining activity and decreasing resilience. Recovery is slowed after each stage of cancer treatment, thereby causing even more inactivity. After a while, a patient enters a phase regarded as a disease in its own right, the so-called fatigue syndrome. Once the cancer treatment is completed, this condition is the biggest problem many patients face—and can be a direct consequence of medically prescribed lack of exercise.

Too much rest can also worsen the primary disease. As we saw, women diagnosed with cancer have a worse prognosis when they put on five kilograms or more during their cancer treatments. Intriguingly, many patients themselves have intuitively sensed that rest was not good at all for them—and decided to do something about it. In the United States many people diagnosed with cancer began exercising hard because they hoped this might improve their quality of life and survival chances. One of the pioneers of this movement is Anna Schwartz. When she fell sick with non-Hodgkin’s lymphoma, she reminded herself of what had often struck her when she worked as a nurse in an oncology clinic. Those patients who, despite the exhausting treatment, regularly left their rooms and stayed physically active “were in a better mood,” Schwartz recalls. And when she had to go through chemotherapy, she forced herself to exercise. She went jogging and played tennis—despite a catheter for the cancer drugs in her body.