Fatigue is often confused with tiredness. Tiredness happens to everyone. It's a feeling you expect after certain activities or at the end of the day. Usually, you know why you are tired and a good night's sleep solves the problem.
Fatigue is a lack of energy throughout the day. It is an unusual or excessive whole-body tiredness not relieved by sleep. It can last just for a short time (a month or less) or stay around for longer (one to six months or longer). Fatigue can prevent you from functioning normally and gets in the way of things you enjoy or need to do.
Cancer-related fatigue is one of the most common side effects of cancer and its treatment. It is not predictable by tumor type, treatment, or stage of illness. Usually, it comes on suddenly, does not result from activity or exertion, and is not relieved by rest or sleep. It may continue even after treatment is complete.
What Causes Cancer-Related Fatigue?
The exact reason for cancer-related fatigue is unknown. It may be related to the disease itself or its treatments.
The following cancer treatments are commonly associated with fatigue:
Chemotherapy. Any chemotherapy drug may cause fatigue, but it may be a more common side effect of drugs such as vincristine and cisplatin. Patients often notice fatigue after several weeks of chemotherapy, but this varies among patients. Some patients feel fatigue for a few days, while others say the problem persists throughout the course of treatment and even after it is completed.
Radiation therapy. Radiation therapy can cause fatigue that increases over time. This can occur no matter where the treatment site is. Fatigue usually lasts from three to four weeks after treatment stops but can continue three months to one year after the treatment is finished.
Combination therapy. More than one cancer treatment at the same time or one after the other increases the chances of developing fatigue.