Progress toward guidelines for the management of fatigue.

Fatigue is a subjective state of overwhelming, sustained exhaustion and decreased capacity for physical and mental work that is not relieved by rest. Cancer-related fatigue has many causes. Included in the causes are the illness itself, the side effects of virtually every treatment, depression, and other biopsychosocial factors. As a result, fatigue is the most common symptom reported by cancer patients in most descriptive studies. In addition to arising from multiple etiologies, fatigue is also multidimensional in its manifestation and impact. Its effect on the quality of life of the patient is comparable to that of pain. Experienced by most patients as an extremely frustrating state of chronic energy depletion, it leads to loss of productivity which can reduce self-esteem. As a subtle and chronic symptom, it also places people at risk for being questioned about the veracity of their complaints, particularly during the post-treatment, disease-free survival period. Patients themselves are reluctant to complain of fatigue, perhaps because they believe little can be done about it, or they wish to avoid drawing attention away from treating their cancer.