Overview

Fatigue is one of the most common complaints of people diagnosed with cancer and cancer survivors. Fatigue occurs in 14 percent to 96 percent of people with cancer, especially those receiving treatment for their cancer. Fatigue is a condition that causes distress and decreased ability to function due to a lack of energy, and has biological, psychological and behavioral causes. People with cancer may express their fatigue in different ways, such as saying they feel tired, weak, exhausted, weary, worn-out, heavy or slow. Health professionals may use terms such as asthenia, fatigue, lassitude, prostration, exercise intolerance, lack of energy and weakness to describe fatigue. Specific symptoms may be physical, psychological or emotional. To be treated effectively, fatigue related to cancer and cancer treatment needs to be distinguished from other kinds of fatigue.

Fatigue may be acute or chronic. Acute fatigue is normal tiredness with occasional symptoms that begin quickly and last for a short time. Rest may alleviate fatigue and allow a return to a normal level of functioning in a healthy individual, but this ability is diminished in people who have cancer. Chronic fatigue is long lasting. Chronic fatigue syndrome describes prolonged debilitating fatigue that may persist or relapse. This illness is sometimes diagnosed in people who do not have cancer. Although many treatment and disease-related factors may cause fatigue, the exact process of fatigue in people with cancer is not known.

Fatigue can become a very important issue in the life of a person with cancer. It may affect how the person feels about him or herself, his or her daily activities and relationships with others, and whether he or she continues with cancer treatment. Patients receiving some cancer treatments may miss work, withdraw from friends, need more sleep, and, in some cases, may not be able to perform any physical activities because of fatigue. Finances can become difficult if people with fatigue need to take disability leave or stop working completely. Job loss may result in the loss of health insurance or the inability to get medical care. Understanding fatigue and its causes is important in determining effective treatment and in helping people with cancer cope with fatigue. Tests that measure the level of fatigue have been developed.

Causes

The causes of fatigue in people with cancer are not known. Fatigue commonly is an indicator of disease progression and is frequently one of the first symptoms of cancer in both children and adults. For example, parents of a child diagnosed with acute lymphocytic leukemia or non-Hodgkin's lymphoma frequently seek medical care because of the child's extreme fatigue. Tumors can cause fatigue directly or indirectly by spreading to the bone marrow, causing anemia, and by forming toxic substances in the body that interfere with normal cell functions. People who are having problems breathing, another symptom of some cancers, may also experience fatigue.

Fatigue can occur for many reasons. The extreme stress that people with cancer experience over a long period of time can cause them to use more energy, leading to fatigue. However, there may be other reasons that cancer patients suffer from fatigue. The central nervous system (the brain and spinal cord) may be affected by the cancer or the cancer therapy (especially biological therapy) and cause fatigue. Medication to treat pain, depression, vomiting, seizures, and other problems related to cancer may also cause fatigue. Tumor necrosis factor (TNF) is a substance that can be produced by a tumor, or may be given to a patient as a treatment for some types of cancer. TNF may cause a decrease in protein stores in muscles causing the body to work harder to perform normal functions, and therefore causing fatigue. There are many chemical, physical, and behavioral factors that are thought to cause fatigue.

Factors Related to Fatigue

It is not always possible to determine the factors that cause fatigue in patients with cancer. Possible factors include the following:

  • Cancer treatment
  • Anemia
  • Medications
  • Weight loss and loss of appetite
  • Changes in metabolism
  • Decreased levels of hormones
  • Emotional distress
  • Difficulty sleeping
  • Inactivity
  • Difficulty breathing
  • Loss of strength and muscle coordination
  • Pain
  • Infection
  • Having other medical conditions in addition to cancer

Cancer treatment

Fatigue is a common symptom following chemotherapy, radiation therapy, biological therapy and surgery.

Several factors have been linked with fatigue caused by chemotherapy. Some people may respond to the diagnosis and treatment of cancer with mood changes and disrupted sleep patterns. Nausea, vomiting, chronic pain, and weight loss can also cause fatigue.

Fatigue has long been associated with radiation therapy, although the connection between them is not well understood. It may be caused the increased need to repair damaged skin tissue. Fatigue usually lessens after the therapy is completed, although not all patients return to their normal level of energy. Patients who are older, have advanced disease, or receive combination therapy (for example, chemotherapy plus radiation therapy) are at a higher risk for developing long-term fatigue.

Biological therapy frequently causes fatigue. In this setting, fatigue is one of a group of side effects known as flu like syndrome. This syndrome also includes fever, chills, muscle pain, headache, and a sense of generally not feeling well. Some patients may also experience problems with their ability to think clearly. The type of biological therapy used may determine the type and pattern of fatigue experienced.

Many people with cancer undergo surgery for diagnosis or treatment. Fatigue is a problem following surgery, but fatigue from surgery improves with time. It can be made worse, however, when combined with the fatigue caused by other cancer treatments.

Anemia

Anemia may be a major factor in cancer-related fatigue and quality of life in people with cancer. Anemia may be caused by the cancer, cancer treatment or may be related to other medical causes.

Nutrition factors

Fatigue often occurs when the body needs more energy than the amount being supplied from the patient's diet. In people with cancer, three major factors may be involved: a change in the body's ability to process food normally, an increased need by the body for energy (due to tumor growth, infection, fever or problems with breathing), and a decrease in the amount of food eaten (due to lack of appetite, nausea, vomiting, diarrhea or bowel obstruction).

Psychological factors

The moods, beliefs, attitudes and reactions to stress of people with cancer can contribute to the development of fatigue. Approximately 40 percent to 60 percent of the cases of fatigue among all patients (cancer patients as well as other patients) are not caused by disease or other physical reasons. Anxiety and depression are the most common psychological disorders that cause fatigue.

Anxiety and fear associated with a cancer diagnosis, as well as its impact on a person's physical, mental, social and financial well-being are sources of emotional stress. Distress from being diagnosed with cancer may be all that is needed to trigger fatigue.

Depression may be a disabling illness that affects approximately 15 percent to 25 percent of people who have cancer. When patients experience depression (loss of interest, difficulty concentrating, mental and physical tiredness, and feelings of hopelessness), the fatigue from physical causes can become worse and last longer than usual, even after the physical causes are gone.

Mental ability factors

Decreased attention span and difficulty understanding and thinking are often associated with fatigue. Attention problems are common during and after cancer treatment. Attention may be restored by activities that encourage rest. Sleep is also necessary for relieving attention problems but it is not always enough.

Sleep disorders and inactivity

Disrupted sleep, poor sleep habits, less sleep at night, sleeping a lot during the day or no activity during the day may contribute to cancer-related fatigue. Patients who are less active during the daytime and awaken frequently during the night report higher levels of cancer-related fatigue.

Medications

Medications other than those used in chemotherapy may also contribute to fatigue. Opioids used in treating cancer-related pain often cause drowsiness, the extent of which may vary depending on the individual. Other types of medications such as tricyclic antidepressants and antihistamines may also produce the side effect of drowsiness. Taking several medications may compound fatigue symptoms.

Assessment

To determine the cause and best treatment for fatigue, the person's fatigue pattern must be determined, and all of the factors causing the fatigue must be identified. The following factors must be included:

  • Fatigue pattern, including how and when it started, how long it has lasted and its severity, plus any factors that make fatigue worse or better
  • Type and degree of disease and of treatment-related symptoms and/or side effects
  • Treatment history
  • Current medications
  • Sleep and/or rest patterns and relaxation habits
  • Eating habits and appetite or weight changes
  • Effects of fatigue on activities of daily living and lifestyle
  • Psychological profile, including an evaluation for depression
  • Complete physical examination that includes evaluation of walking patterns, posture and joint movements
  • How well the patient is able to follow the recommended treatment
  • Job performance
  • Financial resources
  • Other factors (for example, anemia, breathing problems, decreased muscle strength)

Underlying factors that contribute to fatigue should be evaluated and treated when possible. Contributing factors include anemia, depression, anxiety, pain, dehydration, nutritional deficiencies, sedating medications and therapies that may have poorly tolerated side effects. Patients should tell their doctors when they are experiencing fatigue and ask for information about fatigue related to underlying causes and treatment side effects.

Anemia evaluation

There are different kinds of anemia. A medical history, a physical examination and blood tests may be used to determine the kind and extent of anemia that a person may have. In people with cancer, there may be several causes.

Treatment

Most of the treatments for fatigue in cancer patients are for treating symptoms and providing emotional support because the causes of fatigue that are specifically related to cancer have not been determined. Some of these symptom-related treatments may include adjusting the dosages of pain medications, administering red blood cell transfusions or blood cell growth factors, diet supplementation with iron and vitamins, and antidepressants or psychostimulants.

Psychostimulant drugs

Although fatigue is one of the most common symptoms in cancer, few medications are effective in treating it. A health care provider may prescribe medication in low doses that may help patients who are depressed, unresponsive, tired, distracted or weak. These drugs (psychostimulants) can give a sense of well-being, decrease fatigue and increase appetite. They are also helpful in reversing the sedating effects of morphine, and they work quickly. However, these drugs can also cause sleeplessness, euphoria and mood changes. High doses and long-term use may cause loss of appetite, nightmares, sleeplessness, euphoria, paranoid behavior and possible heart problems.

Exercise

Exercise (including light- to moderate-intensity walking programs) helps many people with cancer. People with cancer who exercise may have more physical energy, improved appetite, improved ability to function, improved quality of life, improved outlook, improved sense of well being, enhanced sense of commitment, and improved ability to meet the challenges of cancer and cancer treatment. Exercise may also help patients with advanced cancer, even those in hospice care. More benefit may result when family members are involved with the patient in the physical therapy program.

Activity and rest

Any changes in daily routine require the body to use more energy. People with cancer should set priorities and keep a reasonable schedule. Health professionals can help patients by providing information about support services to help with daily activities and responsibilities. An activity and rest program can be developed with a healthcare professional to make the most of a patient's energy. Practicing sleep habits such as not lying down at times other than for sleep, taking short naps no longer than one hour and limiting distracting noise (i.e. TV or radio) during sleep may improve sleep and allow more activity during the day.

Patient education

Treating chronic fatigue in cancer patients means accepting the condition and learning how to cope with it. People with cancer may find that fatigue becomes a chronic disability. Although fatigue is frequently an expected, temporary side effect of treatment, other factors may cause it to continue. Since fatigue is the most common symptom in people receiving outpatient chemotherapy, patients should learn ways to manage the fatigue. Patients should be taught the following:

  • The difference between fatigue and depression
  • Possible medical causes of fatigue (not enough fluids, electrolyte imbalance, breathing problems, anemia)
  • To observe their rest and activity patterns during the day and over time
  • To engage in attention-restoring activities (walking, gardening, bird-watching)
  • To recognize fatigue that is a side effect of certain therapies
  • To participate in exercise programs that are realistic
  • To identify activities which cause fatigue and develop ways to avoid or modify those activities
  • To identify environmental or activity changes that may help decrease fatigue
  • The importance of eating enough food and drinking enough fluids
  • Physical therapy may help with nerve or muscle weakness
  • Respiratory therapy may help with breathing problems
  • To schedule important daily activities during times of less fatigue, and cancel unimportant activities that cause stress
  • To avoid or change a situation that causes stress
  • To observe whether treatments being used to help fatigue are working

Treatment for anemia

Treatment for fatigue that is related to anemia may include red blood cell transfusions. Transfusions are an effective treatment for anemia, however possible side effects include infection, immediate transfusion reaction, graft-versus-host disease, and changes in immunity. Treatment for anemia-related fatigue, in patients undergoing chemotherapy, may also include drugs that stimulate the production of blood cells such as epoetin alfa.