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Cancer-related fatigue is a subjective symptom of fatigue that is experienced by nearly all cancer patients.
Among patients receiving cancer treatment other than surgery, it is essentially universal. Fatigue is a normal and expected side effect of most forms of chemotherapy, radiation therapy, and biotherapy. On average, cancer-related fatigue is "more severe, more distressing, and less likely to be relieved by rest" than fatigue experienced by healthy people. It can range from mild to severe, and may be either temporary or a long-term effect.
Fatigue may be a symptom of the cancer, or it may be the result of treatments for the cancer.
Some fatigue is caused by cancer treatments. This may show a characteristic pattern. For example, people on many chemotherapy regimens often feel more fatigue in the week after treatments, and less fatigue as they recover from that round of medications. People receiving radiation therapy, by contrast, often find their fatigue steadily increases until the end of treatment.
The National Comprehensive Cancer Network defines cancer-related fatigue as "a distressing persistent, subjective sense of physical, emotional and/or cognitive tiredness or exhaustion related to cancer or cancer treatment that is not proportional to recent activity and interferes with usual functioning".
Treatment depends on the patient's overall situation. A patient who is in active treatment may have different priorities than a person who has completed treatment, or who is at the end of life.
Some management strategies may help all patients and could be supported by the work of an Occupational Therapist. These include scheduling high-priority tasks during the patient's best time of day, using labor-saving devices, delegating tasks to caregivers, and avoiding unimportant activities, so that the patient will have more energy available for other activities.
Patients who are not at the end of life may benefit from physical exercise or physical therapy. Engaging in moderate activity reduces fatigue.
While antidepressants are ineffective at reducing fatigue in non-depressed cancer patients, the stimulant methylphenidate (Ritalin) may reduce fatigue in some patients.
At the end of life, fatigue is usually associated with other symptoms, especially anemia, side effects from many medications and previous treatments, and poor nutritional status. Pain, difficulty breathing, and fatigue form a common symptom cluster. Fatigue often increases as patients with advanced cancer approach death. As a result, people who are dying often sleep much more than a healthy person.
Addressing specific causes
If the fatigue is caused or exacerbated by a specific medical condition, such as anemia, then treatment of that medical condition should reduce the fatigue.
Anemia: Loss of oxygen-carrying red blood cells is a common cause of fatigue. Medications to improve blood production or blood transfusions frequently reduce fatigue.
Emotional distress: Anxiety and depression are strongly associated with fatigue in cancer patients. Psychosocial treatments directed at reducing stress and increasing coping skills may reduce fatigue. Additionally, some patients in active treatment worry that the fatigue indicates treatment failure, and this anxiety may increase their fatigue in a vicious cycle. Education about fatigue as a normal side effect can reassure the patient. Up to 25% of cancer patients will experience depression.
Lack of physical activity: Decreased physical activity can make fatigue worse by reducing endurance and muscle strength. Participating in regular aerobic and muscle-strengthening physical activity both during and after cancer treatment may reduce cancer-related fatigue. Current physical activity guidelines recommend adults with cancer to engage in at least 150 minutes per week of moderate- intensity or 75 minutes per week of vigorous-intensity aerobic physical activity, or an equivalent combination. It is also recommended to perform muscle-strengthening physical activity two to three times a week. Physical activities should be tailored to individual needs and physical abilities.
Side effects from medications: Fatigue and sleepiness are known side effects with some kinds of medications. Sometimes a change of medication, the dose, or the timing of the medication may result in less fatigue. For example, an antihistamine might be taken shortly before sleep, rather than in the middle of the day.
Other medical conditions: Cancer and its treatment usually put intense physical stress on the body, which can exacerbate other medical conditions. Additionally, fatigue may result from an infection.
Fatigue caused by the cancer or its treatment often resolves if treatment is successful. However, some patients experience long-term fatigue. When strict definitions are used, about 20% of long-term, disease-free cancer survivors report fatigue. Under looser definitions, up to half of cancer survivors report fatigue. However, these studies are largely limited to patients with breast cancer, or peripheral stem cell transplant or bone marrow transplant patients, and the incidence may be different for survivors of other cancers.
Experiencing fatigue before treatment, being depressed or anxious, getting too little exercise, and having other medical conditions are all associated with higher levels of fatigue in post-treatment cancer survivors. Receiving multiple types of treatments, such as chemotherapy and radiation, is associated with more fatigue. Older adults have a higher risk of long-term fatigue.
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