Accepting the fatigue that comes with having cancer and the treatments you’ll need for it is difficult. What’s referred to in the medical world as “cancer-related fatigue” (CRF) is both common and a distressing side effect of cancer and cancer treatments, especially because rest and sleep aren’t enough to overcome the problem. 

Cancer-related fatigue can last months or years after cancer diagnosis and treatment. People experiencing CRF describe it as feeling tired, weak, slow, and having no energy. With no means to relieve their symptoms, people with CRF report feeling depressed and helpless. It’s frustrating to be unable to perform regular physical activity like walking, climbing stairs or even eating.

Almost all people receiving cancer treatment, which may include surgery, chemotherapy, radiation therapy and immunotherapy, report symptoms of CRF. The physical, psychological and emotional implications of this long-lasting exhaustion can be deeply disruptive. Some people find it to be the most troublesome of all cancer-related symptoms, more difficult to deal with than other treatment side effects, including nausea and vomiting. 

Fortunately, there are solutions. Because different cancer treatments can also cause different symptoms of CRF, your doctor will work with you to find the type of treatment that’s most helpful to you.

“Fatigue is a potential long-term side effect of cancer,” says Tara Sanft, MD, a medical oncologist and director of Yale Cancer Center’s Cancer Survivorship Program. “At the Survivorship Program, we spend a lot of time tackling issues regarding fatigue related to treatment.” She and her team help patients by developing an individual care plan to help with any number of issues that can result from cancer such as tiredness, appearance, fear of recurrence and getting back to—or trying to start—an exercise regimen.

Cancer-related fatigue (CRF) is a severe form of fatigue among people with cancer. It is described as an overwhelming tiredness, exhaustion and weakness that doesn’t go away with sleep and rest. 

Even though CRF has a lot of the same symptoms as depression, the condition is considered its own primary symptom of cancer and cancer treatment. However, if you are also experiencing depression either from a diagnosis prior to your cancer, or as a result of your cancer, treatment for depression might also help with the symptoms of your CRF. 

Causes of cancer-related fatigue are complex, wide-ranging and not yet fully understood. Lifestyle, including poor nutrition, lack of exercise and alcohol consumption can be factors. CRF is also affected by sleep disturbances, certain medicines and your mental health prior to a cancer diagnosis. Many causes of CRF are linked to the cancer itself or the treatment you’re receiving for your cancer.

Causes of CRF linked to cancer include the following:

• Anemia
• Pain
• Infection
• Trouble breathing
• Problems with other organs, such as the heart, lung, liver, kidneys or brain
• Being less active and loss of muscle and strength

Causes of CRF linked to cancer treatment include the following:   

• Your body needing more energy to repair the damage caused by treatment
• Toxic substances that remain in your body after chemotherapy
• Hormone and protein imbalances caused by hormonal therapies
• Recovery of the immune system following immunotherapy

Sometimes CRF is present even before you realize you have cancer. Symptoms can occur during the following times:

• Before treatment, as a result of the cancer’s physical toll on the body, and the physical and emotional stress of diagnosing your cancer.
• During treatment. It’s common for fatigue as a result of chemotherapy to peak during treatment and then improve until the next treatment, when it will peak again. In radiation therapy, fatigue often gets more severe as treatments continue.
• After treatment, as a result of the cancer treatment’s effect on the body, which could last weeks, months or years.

Symptoms of CRF are often the same as fatigue symptoms in healthy people, except CRF symptoms usually cannot be alleviated by rest and sleep, and can last for months and years. Symptoms include the following:

• Tiredness
• Weakness
• Exhaustion
• Weariness
• Feeling worn-out, heavy and slow
• Having no energy

Cancer-related fatigue can also cause other problems, including impaired memory, the inability to think clearly, lack of concentration, depression, loss of sense of self and reduced physical function.

There is no laboratory test to specifically diagnose cancer-related fatigue, but you should communicate fully and regularly with your doctor about the symptoms you are experiencing in order to gain access to treatments that will help. For example, your doctor can usually diagnose CRF by better understanding the anxiety and stress you’re experiencing surrounding your cancer and cancer treatment, insomnia, pain, and other social and environmental factors affecting your quality of life.

There are several basic laboratory tests your doctor can perform to find out whether your CRF is being caused by an underlying medical issue. These tests are performed by examining your blood under the microscope for signs of anemia, infection, or electrolyte and glucose imbalances.

The goal of CRF treatment is to improve your strength and help you cope with symptoms. Treatments include the following:

• Non-drug treatments, including exercise, counseling to reduce stress and/or anxiety, planning of tasks to reduce physical effort, and relaxation.
• Psychostimulants. These may include drugs taken orally that increase activity of the central nervous system and the body, as well as others that are pleasurable and invigorating, which can be effective in improving CRF symptoms.
• Plant-based treatments, such as medicines derived from plants, including ginseng and guarana.
• Corticosteroids, which are drugs taken to reduce inflammation and improve symptoms related to fatigue.

If cancer-related fatigue is due to cancer treatment, your doctor may also recommend stopping or changing treatment, depending on how effective the treatment plan is on controlling cancer relative to your CRF symptoms.

Yale Medicine medical oncologists who see patients at Yale Cancer Center at Smilow work with patients at the Cancer Survivorship Program to find ways to decrease cancer-related fatigue, which can persist even after treatment is complete. We develop an individualized care plan for each patient with diet and exercise recommendations, which can help increase energy levels to improve quality of life.