Cancer treatment
Anemia
Nutrition factors
Psychological factors
Mental ability factors
Sleep disorders and inactivity
Medications

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.



• Hormone levels that are too low or too high.



• Emotional distress.



• Decline in physical condition.



• Trouble sleeping.



• Inactivity.



• Trouble breathing.



• Loss of strength and muscle coordination.



• Pain and other symptoms.



• High levels of inflammation -causing cytokines.



• Poor nutrition.



• Dehydration.



• Infection.



• Having other medical conditions in addition to cancer.

Fatigue is a common symptom following radiation therapy or chemotherapy. Fatigue may also be a side effect of biologic response modifier therapy, a type of treatment to boost or restore the ability of the immune system to fight cancer, infections, and other diseases. It may be caused by anemia, or the collection of toxic substances produced by cells. In the case of radiation, it may be caused by the increased energy needed to repair damaged skin tissue.

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. Fatigue usually lessens after the therapy is completed, but some fatigue may last for months or years following treatment. 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 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.

Fatigue often occurs when the body needs more energy than the amount being supplied from the patient's diet. In people with cancer, 3 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).

The moods, beliefs, attitudes, and reactions to stress of people with cancer can contribute to the development of fatigue. Approximately 40% to 60% of the cases of fatigue among all patients (patients with cancer 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.

Depression may be a disabling illness that affects approximately 15% to 25% 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. 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. (Refer to the PDQ summaries on Depression ¹ and on Anxiety ² for more information.)

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.

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 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.

Glossary Terms

Cancer that has spread to other places in the body and usually cannot be cured or controlled with treatment.

A condition in which the number of red blood cells is below normal.

A type of drug that blocks the action of histamines, which can cause fever, itching, sneezing, a runny nose, and watery eyes. Antihistamines are used to prevent fevers in patients receiving blood transfusions and to treat allergies, coughs, and colds.

Feelings of fear, dread, and uneasiness that may occur as a reaction to stress. A person with anxiety may sweat, feel restless and tense, and have a rapid heart beat. Extreme anxiety that happens often over time may be a sign of an anxiety disorder.

A desire to satisfy a physical or mental need, such as for food, sex, or adventure.

Treatment to boost or restore the ability of the immune system to fight cancer, infections, and other diseases. Also used to lessen certain side effects that may be caused by some cancer treatments. Agents used in biological response modifier therapy include monoclonal antibodies, growth factors, and vaccines. These agents may also have a direct antitumor effect. Also called biological therapy, biotherapy, BRM therapy, and immunotherapy.

Treatment to boost or restore the ability of the immune system to fight cancer, infections, and other diseases. Also used to lessen certain side effects that may be caused by some cancer treatments. Agents used in biological therapy include monoclonal antibodies, growth factors, and vaccines. These agents may also have a direct antitumor effect. Also called biological response modifier therapy, biotherapy, BRM therapy, and immunotherapy.

The long, tube-shaped organ in the abdomen that completes the process of digestion. The bowel has two parts, the small bowel and the large bowel. Also called intestine.

A term for diseases in which abnormal cells divide without control and can invade nearby tissues. Cancer cells can also spread to other parts of the body through the blood and lymph systems. There are several main types of cancer. Carcinoma is cancer that begins in the skin or in tissues that line or cover internal organs. Sarcoma is cancer that begins in bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue. Leukemia is cancer that starts in blood-forming tissue such as the bone marrow, and causes large numbers of abnormal blood cells to be produced and enter the blood. Lymphoma and multiple myeloma are cancers that begin in the cells of the immune system. Central nervous system cancers are cancers that begin in the tissues of the brain and spinal cord.

The individual unit that makes up the tissues of the body. All living things are made up of one or more cells.

Treatment with drugs that kill cancer cells.

Pain that can range from mild to severe, and persists or progresses over a long period of time.

A substance that is made by cells of the immune system. Some cytokines can boost the immune response and others can suppress it. Cytokines can also be made in the laboratory by recombinant DNA technology and used in the treatment of various diseases, including cancer.

A condition caused by the loss of too much water from the body. Severe diarrhea or vomiting can cause dehydration.

A mental condition marked by ongoing feelings of sadness, despair, loss of energy, and difficulty dealing with normal daily life. Other symptoms of depression include feelings of worthlessness and hopelessness, loss of pleasure in activities, changes in eating or sleeping habits, and thoughts of death or suicide. Depression can affect anyone, and can be successfully treated. Depression affects 15-25% of cancer patients.

The process of identifying a disease, such as cancer, from its signs and symptoms.

Frequent and watery bowel movements.

The things a person eats and drinks.

In medicine, a disturbance of normal functioning of the mind or body. Disorders may be caused by genetic factors, disease, or trauma.

Extreme mental or physical pain or suffering.

A condition marked by extreme tiredness and inability to function due lack of energy. Fatigue may be acute or chronic.

An increase in body temperature above normal (98.6 degrees F), usually caused by disease.

One of many chemicals made by glands in the body. Hormones circulate in the bloodstream and control the actions of certain cells or organs. Some hormones can also be made in the laboratory.

The complex group of organs and cells that defends the body against infections and other diseases.

Invasion and multiplication of germs in the body. Infections can occur in any part of the body and can spread throughout the body. The germs may be bacteria, viruses, yeast, or fungi. They can cause a fever and other problems, depending on where the infection occurs. When the body’s natural defense system is strong, it can often fight the germs and prevent infection. Some cancer treatments can weaken the natural defense system.

Redness, swelling, pain, and/or a feeling of heat in an area of the body. This is a protective reaction to injury, disease, or irritation of the tissues.

A legal drug that is used to prevent, treat, or relieve symptoms of a disease or abnormal condition.

The total of all chemical changes that take place in a cell or an organism. These changes make energy and the materials needed for growth, reproduction, and maintaining health. They also help get rid of toxic substances.

A feeling of sickness or discomfort in the stomach that may come with an urge to vomit. Nausea is a side effect of some types of cancer therapy.

The taking in and use of food and other nourishing material by the body. Nutrition is a 3-part process. First, food or drink is consumed. Second, the body breaks down the food or drink into nutrients. Third, the nutrients travel through the bloodstream to different parts of the body where they are used as "fuel" and for many other purposes. To give the body proper nutrition, a person has to eat and drink enough of the foods that contain key nutrients.

Blockage of a passageway.

A substance used to treat moderate to severe pain. Opioids are like opiates, such as morphine and codeine, but are not made from opium. Opioids bind to opioid receptors in the central nervous system. Opioids used to be called narcotics. An opioid is a type of alkaloid.

PDQ is an online database developed and maintained by the National Cancer Institute. Designed to make the most current, credible, and accurate cancer information available to health professionals and the public, PDQ contains peer-reviewed summaries on cancer treatment, screening, prevention, genetics, complementary and alternative medicine, and supportive care; a registry of cancer clinical trials from around the world; and directories of physicians, professionals who provide genetics services, and organizations that provide cancer care. Most of this information, and more specific information about PDQ, can be found on the NCI's Web site at http://www.cancer.gov/cancertopics/pdq. Also called Physician Data Query.

Having to do with how the mind works and how thoughts and feelings affect behavior.

The overall enjoyment of life. Many clinical trials assess the effects of cancer and its treatment on the quality of life. These studies measure aspects of an individual’s sense of well-being and ability to carry out various activities.

Energy released in the form of particle or electromagnetic waves. Common sources of radiation include radon gas, cosmic rays from outer space, medical x-rays, and energy given off by a radioisotope (unstable form of a chemical element that releases radiation as it breaks down and becomes more stable).

The use of high-energy radiation from x-rays, gamma rays, neutrons, protons, and other sources to kill cancer cells and shrink tumors. Radiation may come from a machine outside the body (external-beam radiation therapy), or it may come from radioactive material placed in the body near cancer cells (internal radiation therapy). Systemic radiation therapy uses a radioactive substance, such as a radiolabeled monoclonal antibody, that travels in the blood to tissues throughout the body. Also called irradiation and radiotherapy.

A problem that occurs when treatment affects healthy tissues or organs. Some common side effects of cancer treatment are fatigue, pain, nausea, vomiting, decreased blood cell counts, hair loss, and mouth sores.

The response of the body to physical, mental, or emotional pressure. This may make a person feel frustrated, angry, or anxious, and may cause unhealthy chemical changes in the body. Untreated, long-term stress may lead to many types of mental and physical health problems.

A procedure to remove or repair a part of the body or to find out whether disease is present. An operation.

An indication that a person has a condition or disease. Some examples of symptoms are headache, fever, fatigue, nausea, vomiting, and pain.

A set of symptoms or conditions that occur together and suggest the presence of a certain disease or an increased chance of developing the disease.

Treatment.

A group or layer of cells that work together to perform a specific function.

Having to do with poison or something harmful to the body. Toxic substances usually cause unwanted side effects.

A type of drug used to treat depression.

An abnormal mass of tissue that results when cells divide more than they should or do not die when they should. Tumors may be benign (not cancer), or malignant (cancer). Also called neoplasm.

To eject some or all of the contents of the stomach through the mouth.