Fatigue is a vague feeling of being tired, weak, or exhausted. It is often a symptom
of cancer when cancer is first diagnosed, or when cancer progresses. It is also the
most common side effect of cancer treatment. Fatigue does not mean the cancer is getting
worse, or that the cancer treatment isn't working.
Some people with cancer have described fatigue as being tired to the bones or hitting
a wall. Others say it is the most distressing side effect of cancer treatment. Fatigue
is different for everyone. It is important that the person who is experiencing it
describes how he or she feels. Fatigue may cause decreased ability to work or do physical
activity, be involved with family, socialize with friends, or complete daily activities.
Sometimes it even causes people to miss cancer treatments. If the person with cancer
is easily distracted and unable to concentrate on mental work or activity, then he
or she may have attentional fatigue. This may also be called chemo brain.
Depending on its cause, fatigue can come and go or stay constant for awhile. Fatigue
from chemotherapy tends to happen a few days after the treatment, peaks, and then
gets better before the next treatment. Fatigue from radiation usually doesn't happen
right away. It may develop over the first 2 to 3 weeks of treatment and then increase
as the treatment continues. It may last 3 months or more after the treatment is finished.
Attentional fatigue can last up to 2 or 3 years after treatment is completed.
Causes of fatigue
We currently understand some of the causes of fatigue, but not all of them. Fatigue
may be related to physical changes caused by cancer or its treatment (chemotherapy,
biotherapy, radiotherapy, or surgery). It is reported that the fatigue people get
when receiving cancer treatment is more severe than the fatigue healthy people get.
In addition, this fatigue lasts longer and is not relieved by sleep.
Studies have shown that low hemoglobin is also related to fatigue. Hemoglobin carries
oxygen in the blood, so if it is low, the body cells do not get as much oxygen as
they need. In addition, people who are not well-nourished, who don't drink enough
fluid and are dehydrated, or who are not able to move around much tend to have fatigue
more easily. Uncontrolled pain, depression, and insomnia can also cause fatigue. Finally,
the way a person handles stress, thinks, or behaves can influence fatigue.