Cancer is a term used to describe hundreds of diseases that share the common feature of uncontrolled, abnormal growth and proliferation of cells, which in some cases can spread to distant anatomical sites (metastasis). The initial symptoms of cancer can be localized, as in the cough of the person with lung cancer, or systemic, as in the drenching night sweats of Hodgkin’s lymphoma. Following treatment, the symptoms of cancer can result from the progression of the illness or from the side effects of the treatment itself. Treatment options for cancer include surgery, radiation, chemotherapy, and immunotherapy, either singly or in combination, and can be designed to achieve a cure or to control the disease and relieve symptoms. Cancer is considered cured when a remission is thought to be permanent, but many cancers are considered cured if the patient does not have a recurrence within five years after treatment. Recurrence of cancer occurs when one or more cancer cells survive following treatment and subsequently proliferate over time.
Virtually all individuals with cancer can benefit from rehabilitation and exercise. The goals of exercise therapy vary depending on whether an individual is receiving initial treatment for a new diagnosis, is in remission, or is receiving treatment for a recurrence. Moreover, the response to exercise and adaptability to training are influenced by whether the individual has local or metastatic disease and by the side effects of the particular form of treatment. The specific roles and applications of exercise programming for individuals with cancer are complex and require a thorough understanding of the person’s past and current medical history, treatments, medications, signs and symptoms, and functional capacity as well as consideration of comorbidities. Exercise management for persons with cancer requires extensive individualization by the exercise professional. The key to recovery for people with cancer is to have hope. Perhaps there is no greater example of hope for cancer survivors than Lance Armstrong’s five victories in the Tour de France, which proved that it is indeed possible to have advanced cancer, undergo extensive treatment, and go on to achieve extraordinary levels of human performance. While most individuals with cancer will not exhibit the athletic prowess of Lance Armstrong, they will achieve a variety of health benefits from formal exercise programming and by adopting an active and fit way of living.
Individuals with cancer, as well as cancer survivors, often have disease- or treatment-specific physical limitations that pose challenges to exercise. Tumors can involve any part of the body, and their effect on the exercise response is directly related to the tissues affected. Pain is common when a tumor involves the musculoskeletal system; shortness of breath is common with lung involvement; neural deficits and seizures are common when the central nervous system and brain are involved; and anemia is common when bone marrow is affected. Easy fatigability is common during treatment, in the recovery following treatment, and in advanced cancer. The specific effects of cancer on the exercise response are determined by the tissue(s) affected and by the extent of involvement. The result is often exercise intolerance, but the limiting factors can be varied.
The side effects of anticancer therapy also affect the exercise response. Some side effects may occur early during treatment and then resolve once treatment ends, whereas other side effects may occur late during the treatment period and may persist for some time thereafter or may be permanent (see table 27.1). Amputations result in permanent disability; radiation and chemotherapy can cause permanent scar formation in joints and lung and heart tissues; and drug-induced cardiomyopathies and anemia can cause a permanent limitation in cardiovascular function.
|Acute and Chronic Treatment Effects
Loss of flexibility
|Scar tissue buildup at radiation site, including cardiac and lung scarring
Loss of flexibility
||Weight gain or loss
Exercise training is safe and beneficial for cancer patients when the exercise is individualized to suit the characteristics of the person. For those under-going therapy for cancer, exercise training should have the objectives of maintaining strength, endurance, and level of function. For cancer survivors who have completed treatment, exercise training should have the objective of returning them to their former level of physical and psychological function. Studies have shown that regular, moderate-intensity aerobic exercise during cancer therapy results in reduced levels of fatigue, greater body satisfaction, maintenance of body weight, improved mood, less side effect severity, improved aerobic capacity, and a higher quality of life.
Aerobic and resistance exercise programs have the potential to improve balance and bone remodeling and to reduce muscle weakness and the muscle-wasting effects of glucocorticoids that are often part of the treatment regimen. Significant improvements in aerobic capacity, as measured by a 12 min walk, have been observed in clients who participated in an aerobic exercise programs, both home based and supervised. In contrast, people who followed the motto of “get more rest” showed declines of as much as 25% in aerobic capacity during treatment. Individuals undergoing intensive cancer therapy benefit from low- to moderate-intensity aerobic and resistance exercise. Despite the significant fatigue that cancer patients experience, exercise reduces fatigue and improves aerobic capacity, mood, and quality of life.
The effects of exercise in individuals with cancer have been studied in patients receiving many different forms of therapy for different cancers. Results of exercise studies during and following cancer treatment have shown improvements in
- shoulder range of motion,
- muscle strength,
- treatment-related side effects (e.g., nausea, pain, fatigue),
- aerobic capacity,
- weight control,
- body image,
- sense of control,
- depression and mood, and
- quality of life.
The effects of exercise on children receiving cancer treatment have not been extensively studied. However, survivors of childhood leukemia have been observed to have mild, persistent cardiovascular compromise as a result of therapy. This does not usually impair function during exercise of moderate intensity but may hinder elite-level athletic performance. Nonetheless, aerobic capacity and submaximal performance of both children and adults should significantly improve after a scientifically sound, step-by-step exercise training program. A concern with adult cancer survivors is that they often have comorbid conditions such as coronary artery disease, hypertension, diabetes, or hyperlipidemia. Some cancer treatments also increase risks for cardiovascular disease and death from myocardial infarction. These comorbid conditions may actually influence exercise prescription and management more than the history of cancer does.
Cancer treatment usually includes some combination of surgery, radiation therapy, chemotherapy, and immunotherapy. While many treatments have become more targeted to the type of tumor, most continue to cause significant side effects.
Surgery can cause many side effects that clients need to learn to accommodate to within their exercise routine. In the acute stage, pain and loss of flexibility may be the primary side effects. Adequate pain control is critical for the client to be able to begin a basic flexibility and exercise program. Light exercise helps to hasten recovery. Long-term side effects of surgery can be related to pain from amputation and from motor and sensory nerve damage. Exercise programs may need to be adjusted for these physical changes and the client educated in how to move and maximize his or her abilities.
Radiation is given in multiple doses, usually over several weeks. The effects of radiation therapy are cumulative over time. Fatigue gradually increases during the course of radiation therapy. Skin changes such as radiation dermatitis usually become evident toward the middle or end of treatment. These side effects are generally mild to moderate and manageable with clinical intervention. Radiation dermatitis can be irritated with perspiration, and the area may need to be covered with gauze or a bandage to keep it dry. More serious side effects are uncommonly seen; these can include loss of flexibility in irradiated joints and cardiac or lung scarring, or both.
Chemotherapy and immunotherapy are generally given in combinations of drugs that have different mechanisms of action and side effect profiles. The severity of side effects depends on the dose of drug, the pharmacological profile, and to some extent the individual characteristics of the person. Most chemotherapy and immunotherapy drugs cause anemia, fatigue, and nausea, and many cause myopathies and neuropathies (e.g., vincristine, paclitaxel, docetaxel). Some medications have dose-limiting toxicities (i.e., doxorubicin, bleomycin) that limit the amount of drug that can be given to prevent cardiomyopathy and pulmonary fibrosis. Corticosteroids are commonly given with chemotherapy to reduce some of the side effects or reduce tumor volume. Glucocorticoids (decadron, prednisone) contribute to muscle weakness, wasting, and changes in body composition that undoubtedly also influence balance and gait.
The exercise prescription needs to take into account where an individual is in his or her treatment cycle, how well the side effects are being managed, and any physical changes that may put the person at risk during exercise. If chemotherapy is causing neuropathy, balance safety issues need to be considered. Individuals on treatment are often limited by muscle weakness and pain from the tumor, the surgery, or the therapy itself. People are often in a debilitated state, and their ability to walk or perform other functional tests may be limited by the disease or treatment and may necessitate alternative modes of testing and training. Exercise prescription should include slow progression, flexibility surrounding medical management, and adaptability to changes in the client’s health status.