Causes of Fatigue in Cancer Patients
Side effects related to nutrition may cause or increase fatigue.
The body's energy comes from food. Fatigue may occur if the body does not take in enough food to give the body the energy it needs. For many patients, the effects of cancer and cancer treatments make it hard to eat well. In people with cancer, three major factors may affect nutrition:
- A change in the way the body is able to use food. A patient may eat the same amount as before having cancer, but the body may not be able to absorb and use all the nutrients from the food. This is caused by the cancer or its treatment.
- A decrease in the amount of food eaten because of low appetite, nausea, vomiting, diarrhea, or a blocked bowel.
- An increase in the amount of energy needed by the body because of a growing tumor, infection, fever, or shortness of breath.
Anxiety and depression are the most common psychological causes of fatigue in cancer patients.
The emotional stress of cancer can cause physical problems, including fatigue. It's common for cancer patients to have changes in moods and attitudes. Patients may feel anxiety and fear before and after a cancer diagnosis. These feelings may cause fatigue. The effect of the disease on the patient's physical, mental, social, and financial well-being can increase emotional distress.
About 15% to 25% of patients who have cancer get depressed, which may increase fatigue caused by physical factors. The following are signs of depression:
- Feeling tired mentally and physically.
- Loss of interest in life.
- Problems thinking.
- Loss of sleep.
- Feeling a loss of hope.
Some patients have more fatigue after cancer treatments than others do.
Fatigue may be increased when it is hard for patients to learn and remember.
During and after cancer treatment, patients may find they cannot pay attention for very long and have a hard time thinking, remembering, and understanding. This is called attention fatigue. Sleep helps to relieve attention fatigue, but sleep may not be enough when the fatigue is related to cancer. Taking part in restful activities and spending time outdoors may help relieve attention fatigue.