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Cancer-Related Fatigue

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Cancer-related fatigue is common in cancer patients. Fatigue is often confused with tiredness. Tiredness happens to everyone -- it's a feeling you get after doing certain things or at the end of the day. Usually, you know why you're tired, and a good night's sleep solves the problem.

Fatigue is a daily lack of energy or whole-body tiredness that doesn’t go away with sleep. It can be acute (lasting a month or less) or chronic (lasting up to 6 months or longer). Fatigue can prevent you from doing normal, daily things and affects your quality of life.

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Cancer-related fatigue is one of the most common side effects of cancer and cancer treatment. Usually, it comes on suddenly, and it happens even if you haven't been active. It may continue even after you are done with treatment.

What Causes Cancer-Related Fatigue?

Tumor cells steal calories and nutrients from normal cells, leading to fatigue. Weight loss and a smaller appetite are also common with cancer.

Also, the following cancer treatments can cause fatigue:

  • Chemotherapy. Any chemotherapy drug can cause fatigue. In some patients, fatigue lasts a few days, while others say fatigue lasts throughout treatment and even after the treatment is over.
  • Radiation. Radiation can cause fatigue that gets worse over time. Fatigue usually lasts from 3 to 4 weeks after treatment stops, but it can continue for up to 3 months. 
  • Hormone therapy can cause fatigue by depriving the body of estrogen. It can last through treatment or longer.
  • Bone marrow transplant. This aggressive form of treatment can cause fatigue that lasts up to 1 year.
  • Biological therapy. Interferons and interleukins in high amounts can lead to persistent fatigue.
  • Combination therapy. Getting more than one cancer treatment at the same time or one after the other also increases the chances of having fatigue.
  • Surgery. Everyone recovers from surgery at different rates. This can also cause some fatigue.

What Else Contributes to Fatigue?

Here are some other things that may contribute to fatigue:

  • Side effects of treatments (such as nausea, vomiting, mouth sores, taste changes, heartburn, or diarrhea) can lower the amount of nutrition you get, leading to fatigue.
  • Cancer treatments can cause anemia, a blood disorder that causes fatigue because your body's cells don’t get the oxygen they need.
  • If your thyroid gland is underactive, your metabolism may slow down so much that your body does not burn food fast enough to provide energy. This is a common condition in general, but it can also happen after radiation therapy to the lymph nodes in the neck.
  • Medicines used to treat side effects such as nausea, pain, depression, anxiety, and seizures can cause fatigue.
  • Being less active and having problems moving around can lead to fatigue in older people. Younger people in treatment sometimes overexert themselves and bring on fatigue.
  • Hormonal changes related to medicine, including cancer medicines, can cause fatigue.
  • Chronic, severe pain increases fatigue.
  • Stress can make fatigue worse. Stress can result from dealing with cancer. Fatigue often happens when patients try to keep their normal daily routines and activities during treatment. Changing your activities can help conserve energy.

Depression and fatigue often go hand in hand, but it may not be clear which started first. One way to sort this out is to try to understand your depressed feelings and how they affect your life. If you are depressed all the time, were depressed before your cancer diagnosis, or are preoccupied with feeling worthless and useless, you may need treatment for depression.

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