Martin E. Liebling, M.D., FACP
Fatigue is the most common symptom experienced by patients diagnosed with cancer. It can be a symptom of the disease or a side effect caused by treatment. Fatigue may also indicate that cancer has spread (metastasized) to other parts of the body.
Fatigue can seriously impede normal functioning and interfere with a patient’s ability to maintain healthy relationships or derive pleasure from activities. It is characterized by more than just a feeling of tiredness. It is defined as a complete lack of energy or feeling of debilitating tiredness. Feelings of fatigue vary for every individual and may be more severe in some patients than others. It also may be accompanied by other symptoms, such as headaches and irritability.
Diagnosis of fatigue in a patient typically begins with a review of the medical history and a physical examination. Factors important in the history include type and stage of cancer, treatments and pattern of fatigue. To accurately assess fatigue, the physician may ask patients to rate their fatigue on a scale of zero to 10, where a rating of 10 indicates maximum fatigue. Because all of the cancer-specific causes of fatigue have not been determined, the treatments are designed to address physical symptoms and emotional difficulties. Common treatments include psychostimulant drugs, exercise and adhering to an activity and rest schedule.
Fatigue is defined as a complete lack of energy or feeling of debilitating tiredness. It is the most common symptom of cancer, affecting the majority of patients. Often, fatigue is among the first symptoms of cancer in children and adults alike. It also may indicate that an individual’s cancer has progressed.
In addition to being associated with cancer and its various treatments and other diseases, fatigue may be a normal physical response to factors such as:
- Lack of sleep
- Physical exertion
- Stress or anxiety
Cancer-related fatigue can be long-term (chronic) or short-term (acute), with symptoms appearing suddenly and lasting only a short period of time (e.g., during cancer treatment). Fatigue may be more common and severe in patients who have advanced, metastatic (the cancer has spread to other tissues and organs in the body) or recurrent cancer.
According to the American Cancer Society (ACS), research has shown that approximately 90 percent of cancer patients receiving treatment have fatigue. These treatments included radiation therapy, chemotherapy, immunotherapy or bone marrow transplants. Thirty to 75 percent of cancer survivors also reported fatigue for months to years after the completion of treatment.
Research indicates that fatigue associated with cancer and cancer treatments differs greatly from the general feeling of tiredness that everyone experiences at some point in their lives. Unlike general fatigue, cancer-related fatigue is not easily relieved, and can seriously impede normal functioning and interfere with a patient’s ability to:
- Concentrate at work or school
- Perform household chores
- Maintain normal relationships
- Derive pleasure from favorite activities
Even though fatigue can greatly affect patients’ lives, many individuals do not report it to their caregivers or healthcare professionals. Treatment options may be available for cancer patients suffering from fatigue therefore, it is important that the condition be addressed.
Other fatigue-related symptoms
Patients usually characterize cancer-related fatigue as a feeling of lack energy or feeling weak, tired, worn-out, exhausted, weary or slow. Fatigue may be associated with an increased need for rest or the inability to regain energy after rest periods.
Psychological symptoms associated with fatigue may include:
- Lack of motivation
There are also physical responses to fatigue, including:
- Sleep disturbances, such as the inability to sleep or oversleeping
- Feeling of heaviness in the arms and legs
- Muscle pain
Fatigue as a symptom of cancer
Cancer contributes to fatigue in a number of ways. The effect of cancer on the body’s organ systems, for instance, can result in fatigue. Cancer may also contribute to fatigue by indirectly affecting the metabolism. For example, a tumor can cause the body to function in a hypermetabolic (overactive) state, resulting in fatigue, among other symptoms. In addition, some cancers can cause breathing problems associated with fatigue.
Fatigue may be a symptom of advanced cancer, but it can be caused by persistent blood loss, as is sometimes the case with stomach or colorectal cancers. It is also often the first sign of cancers such as acute lymphocytic leukemia (a cancer of the blood) and non-Hodgkin’s lymphoma (cancer of the lymphoid tissue) in children.
Other ways cancer may cause fatigue include:
- Anemia. A condition caused by the blood’s shortage of hemoglobin, the part of a red blood cell that transfers oxygen from the lungs to the bodily tissues. According to the American Cancer Society (ACS), anemia is defined as a blood hemoglobin level under 12 grams/deciliter (g/dL). However, many individuals do not experience symptoms of anemia until their hemoglobin level drops below 11 g/dL. Anemia-related fatigue occurs when the tissues in the body do not receive adequate oxygen. Anemia can be caused by the cancer itself because of the immune system’s response to the cancer cells. It also may be the result of cancer treatments, which can suppress the bone marrow.
- Nutrition factors. When the patient’s diet does not supply enough nutrients and calories to fulfill the body’s demands, fatigue typically results. Poor nutrition in cancer patients is usually due to the following factors:
- The body is unable to process food normally.
- Energy needs have increased because of fever, infection, tumor growth or breathing problems.
- Less food is eaten or absorbed because of nausea, vomiting, decreased appetite, diarrhea and other symptoms that may be caused by the cancer or treatments.
- The body is unable to process food normally.
- Psychological factors. Many psychological factors related to cancer can contribute to the development of fatigue in patients, including a person’s attitudes, moods or beliefs. In addition, reaction to stress may result in fatigue.
- According to the National Cancer Institute (NCI), approximately 15 to 20 percent of cancer patients have depression, a disabling illness often accompanied by fatigue. Other psychological factors, such as the anxiety frequently associated with the diagnosis of cancer and fears about upcoming treatments, can trigger fatigue in patients.
- Sleep disorders/inactivity. Cancer-related factors, such as little or no activity and sleep disruptions that include poor sleep habits, naps and insufficient night sleep may contribute to fatigue. Cancer patients who are inactive during the day and awaken frequently at night report higher levels of fatigue.
- Pain. Many cancer patients experience chronic pain, which can cause several factors that contribute to fatigue, such as:
- Reduced activity
- Decreased appetite
- Sleep problems
It is important to note that not all fatigue is associated with cancer. Many other illnesses and medical problems can contribute to fatigue, such as heart or kidney failure.
Fatigue as a cancer treatment side effect
Cancer treatments can also contribute to fatigue in a variety of ways. For instance:
- Decreased nutrition from treatment side effects, such as nausea, vomiting, taste changes and mouth sores, can cause reduced energy or fatigue in some patients.
- Individuals may experience treatment-induced anemia, which can promote feelings of extreme exhaustion.
- Cancer treatment can reduce a patient’s attention span and concentration, and impact other mental abilities. These factors are frequently associated with fatigue.
The following common treatments may contribute to fatigue:
- Surgery. Fatigue associated with cancer surgery has not been well studied. However, anxiety and fear about the surgery and the numerous diagnostic tests performed beforehand can cause preoperative fatigue in some patients. After surgery, fatigue may result from:
- Pain and discomfort
- Anesthesia and medications
- Sleep disruptions
- Poor appetite and nutrition
- Increased energy demands of recovery
- Chemotherapy. This treatment uses powerful drugs to destroy cancer cells. These drugs are typically administered either intravenously (IV) or orally. About 90 percent of cancer patients who receive chemotherapy experience fatigue, according to the American Cancer Society (ACS). The most severe fatigue usually occurs in the 24 to 72 hours immediately following the administration of chemotherapy. This pattern may vary depending on the:
- Type of cancer
- Medication and schedule
- Method of administering the medication
- Extent of side effects
- General health of the patient
- Radiation therapy. This treatment uses high-energy x-rays to shrink or eliminate cancer cells. Approximately 90 percent of cancer patients who receive radiation therapy will experience fatigue, according to the ACS. Fatigue during radiation therapy may be due to decreased function of the thyroid gland from the treatment if the gland is in the radiation field.
Unlike chemotherapy-related fatigue, which occurs within 72 hours of treatment, fatigue associated with radiation therapy typically begins at the end of the second week or the beginning of the third week of treatment. The fatigue may gradually increase over time. Patterns of fatigue vary among patients as some individuals experience a peak and plateau in fatigue between the fourth and sixth weeks of treatment. Others continue to experience fatigue for up to three months after treatment. As treatment increases, patients may feel worse instead of better. It is important to note that this is not an indication that radiation therapy is ineffective.
- Biotherapy. Certain biotherapy treatments, such as interleukin and interferon, are associated with increased fatigue because they are external cytokines. Cytokines are natural cell proteins or products that are usually released by the white blood cells in response to inflammation and infection. When administered in high amounts, as is common during biotherapy treatment, the cytokines may cause persistent fatigue among other symptoms. Fatigue related to biotherapy increases gradually over the course of treatment. Therefore, adjustments in treatment schedules may become necessary over time to help decrease fatigue.
- Transplants. Although fatigue associated with bone marrow and stem cell transplants has not been well studied, some cancer patients report that transplant-related fatigue is more severe than the fatigue associated with other cancer treatments.
- Hormonal therapies. There have been very few studies regarding the relationship between fatigue and hormonal therapy in cancer patients. However, the hormone changes caused by this treatment can trigger hot flashes in both men and women, which may disrupt sleep and promote fatigue. In addition, hormonal therapies may cause psychological changes, such as depression, which can have fatigue as a side effect.
- Combination therapies. Cancer patients who receive combination therapy (e.g., chemotherapy and radiation therapy) may experience severe fatigue. These treatments affect the patient’s body in different ways. The combination not only demands more time for the actual treatment but also can increase the side effects.
- Medications. Some medications other than chemotherapy drugs can also contribute to fatigue in cancer patients. For instance, analgesics and opioids, which are commonly prescribed to alleviate cancer-related pain, can promote drowsiness in some patients. Although the extent of medication-related fatigue varies among patients, taking multiple medications with many side effects may further exacerbate fatigue in some individuals.
Diagnosis methods for fatigue
In individuals who have cancer, increased fatigue may be an indicator that the disease has progressed.
Diagnosis of fatigue typically begins with a detailed medical history and discussion with the patient about the condition. Patients should also report any additional symptoms that make fatigue worse, such as:
- Shortness of breath
- General weakness
To accurately assess fatigue, physicians may ask patients to rate their fatigue on a scale of zero to 10, where a rating of 10 indicates maximum fatigue. Patients who do not have cancer may be evaluated for other conditions associated with fatigue, such as kidney problems. When patients have cancer, physicians evaluate other factors, such as:
- The pattern of fatigue (e.g., when did the fatigue begin, how long has the fatigue lasted)
- The type and stage of cancer
- Treatment history
- Current medications
- Eating habits
- Daily activities
Additionally, the National Comprehensive Cancer Network(NCCN) has recognized five primary conditions that often accompany cancer-related fatigue, and should be evaluated by a physician. These include:
- Emotional distress
- Sleep problems
- Low thyroid gland function
Treatment options for cancer-related fatigue
Because the cancer-specific causes of fatigue have not been determined, the treatments for fatigue in cancer patients primarily address the physical and psychological symptoms. Common treatments include:
- Psychostimulant drugs and emotional support. Physicians may prescribe low doses of psychostimulant drugs for fatigued cancer patients. These medicines may help alleviate depression, unresponsiveness, distraction, weakness and exhaustion in some patients. They may also increase a patient’s appetite. It is important for patients to care for their emotional needs as well as their physical ones. Therefore, patients may also benefit from mental health counseling and/or cancer support groups.
- Anemia treatment. Treatment for anemia-related fatigue may include medications, such as epoetin alpha drugs, which stimulate red blood cell production and boost energy levels of chemotherapy patients, and, in severe cases, transfusions of red blood cells.
- Exercise. Many cancer patients can help combat fatigue with regular exercise, which can:
- Improve their mood
- Increase their energy
- Improve their endurance, strength and stamina
- Increase their appetite
- Prepare them for the challenges of cancer and its treatments
- Bone metastasis (cancer has spread to the bones)
- Reduced immune system function
- Low platelet count (the blood cells that promote clotting)
- Other complications of treatment
- Activity and rest. Cancer patients who experience fatigue should prioritize their activities and adhere to a regular schedule because changes in daily routine require additional energy. The physician can help devise an activity and rest program that allows the patient to conserve the maximum amount of energy. Patients may reduce fatigue and improve their sleeping habits by:
- Lying down only when ready for sleep
- Limiting nap times during the day to allow sleeping at night
- Increasing activity level during the day
- Eliminating distractions during sleep times
- Eliminating foods at bedtime that could interfere with sleep
- Lying down only when ready for sleep
- Hydration and nutrition. Patients should drink a minimum of eight glasses of liquids every day to remain sufficiently hydrated and eliminate the cellular waste products from metabolism and treatment that may be related to fatigue. They should also eat a balanced and nutritious diet with enough calories, complex carbohydrates (vegetables and whole grains), proteins, fats and vitamins to provide sustained energy sources and help the body meet its escalating energy demands. Patients may choose to speak with a dietician regarding ways to maximize their nutritional intake.
- Patient education and counseling. Because chronic fatigue is common among cancer patients, individuals should learn methods for managing this symptom, such as:
- Learning how to distinguish between fatigue and depression
- Monitoring the level of fatigue and contact a physician if the severity increases
- Familiarizing themselves with potential medical causes of fatigue (e.g., breathing problems, anemia, etc.)
- Observing daily patterns of rest and activity
- Engaging in activities to restore attention, such as gardening or bird-watching
- Eating a sufficient amount of food and drinking plenty of fluids
- Receiving physical or respiratory therapy as needed
- Enlisting the help of others when errands and housework become too difficult
- Learning how to distinguish between fatigue and depression
Questions for your doctor about fatigue
Preparing questions in advance can help patients have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions about fatigue:
- Are there any medical reasons for my fatigue?
- Will my cancer or treatments likely cause fatigue?
- How common is fatigue with my type of cancer or treatment?
- Will my fatigue worsen with treatments?
- How long will my fatigue last?
- Are there any medications that can help reduce my fatigue?
- Are there any lifestyle changes that may help me with this condition?
- How will I know if my fatigue indicates a serious problem?
- Can fatigue indicate that my cancer has returned?
- Can you refer me to some support groups or counseling?