Molecular mechanisms in cytotoxic drug induced fatigue

Fatigue is today the most common and incapacitating side effect in patients treated with cytotoxic drugs. Fatigue affects both physical and psychosocial function and reduces the patients' quality of life. The symptom severity is dependent on cancer type, cytotoxic drugs given and doses, comorbidity and the presence and severity of other symptoms like pain, insomnia, depression, anxiety, diarrhea. Risk factors also include female gender and young age. The mechanisms explaining fatigue is still mostly unknown and there is no general treatment to alleviate the symptoms, although effective treatment of coexisting symptoms and easy exercise will make some benefit. The present survey discusses the pathophysiology and epidemiology of fatigue as well as gives information on its biochemical mechanisms. This also opens up for new targets for treatment.