Fatigue (PDQ®): Supportive care - Health Professional Information [NCI] - Contributing Factors
Table 1. Nutrition/Energy Factors
|Altered ability to process nutrients||Impaired glucose, lipid, and protein metabolism|
|Increased energy requirements||Tumor consumption of and competition for nutrients|
|Hypermetabolic state due to tumor growth|
|Decreased intake of energy sources||Anorexia|
Numerous factors related to the moods, beliefs, attitudes, and reactions to stressors of people with cancer can also contribute to the development of chronic fatigue. Anxiety and depression are the most common comorbid psychiatric disorders of CRF. Often, fatigue is the final common pathway for a range of physical and emotional etiologies.
Depression can be a comorbid, disabling syndrome that affects approximately 15% to 25% of persons with cancer. The presence of depression, as manifested by loss of interest, difficulty concentrating, lethargy, and feelings of hopelessness, can compound the physical causes for fatigue in these individuals and persist long past the time when physical causes have resolved. Anxiety and fear associated with a cancer diagnosis, as well as its impact on the person's physical, psychosocial, and financial well-being, are sources of emotional stress. Distress associated with the diagnosis of cancer alone may trigger fatigue. A study of 74 early-stage breast cancer patients with no history of affective disorder, assessed various symptoms of adjustment approximately 2 weeks after diagnosis; about 45% noted moderate or high levels of fatigue. This fatigue may have been secondary to the increased cognitive strain of dealing with the diagnosis or to insomnia, reported as moderate-to-severe by about 60% of the patients. Fatigue may, therefore, begin before treatment as a result of worry or other cognitive factors, both primary and secondary to insomnia. Various forms of treatment may compound this fatigue. Fatigue may also be increased in cancer survivors above that seen in the general population.[42,43] In testicular cancer survivors, anxiety and depression were predictive of fatigue, suggesting a possible role for psychiatric intervention in fatigue management. (Refer to the PDQ summaries on Depression and Adjustment to Cancer: Anxiety and Distress for more information.)
Psychologic and symptom distress have also been found to be significant predictors of fatigue.[45,46] In a study of 101 women about to undergo surgery for breast cancer, younger age, presurgery distress, and expectations about fatigue significantly predicted fatigue levels 1 week after surgery. In the regression model, age, distress and expectancy each uniquely contributed to fatigue, with distress and expectancy accounting for 25% of the variance.[Level of evidence: III] In a longitudinal study with women who had gynecologic cancer, symptom and psychologic distress significantly predicted fatigue before, during, and after treatment with chemotherapy, explaining up to 80% of the variance in fatigue scores after chemotherapy treatment.