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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.
  • 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.
  • Heart trouble.
  • Having other medical conditions in addition to cancer.

Cancer treatment

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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.

Studies have reported that patients have the most severe fatigue around mid-way through all the cycles of chemotherapy. Fatigue decreases after chemotherapy is finished, but patients often don't feel back to normal even 30 days after the last treatment.

Fatigue during cancer treatment may be increased by the following factors:

  • Pain.
  • Depression.
  • Anxiety.
  • Anemia. Some types of chemotherapy keep the bone marrow from making enough new red blood cells, causing anemia (too few red blood cells to carry oxygen to the body).
  • Lack of sleep caused by certain anticancer drugs.

Many patients undergoing radiation therapy report fatigue that keeps them from being as active as they want to be. After radiation therapy begins, fatigue usually increases until mid-way through the course of treatments and then stays about the same until treatments end. 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.

In men with prostate cancer, fatigue was increased by having the following symptoms before radiation therapy started:

  • Poor sleep.
  • Depression.
  • Anxiety.
  • Pain.

In women with breast cancer, fatigue was increased by the following:

  • Working while undergoing radiation therapy.
  • Having children at home.
  • Depression.
  • Anxiety.
  • Poor sleep.
  • Younger age.
  • Being underweight.
  • Having advanced cancer or other medical conditions.

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.


WebMD Public Information from the National Cancer Institute

Last Updated: May 16, 2012
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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