Morning fatigue was higher for those who:
- Had more trait anxiety.
- Were experiencing sleep disturbance.
- Were younger.
- Had lower body mass indices.
Advanced disease and comorbidities also added to the severity of morning fatigue.[Level of evidence: III]
A number of research studies document the existence of a fatigue syndrome that is not specific to the disease type or radiation site and that demonstrates a gradual decline in fatigue in the patient after treatment is completed.[15,17,18,19,20] Some of these studies suggest, however, that not all patients return to pretreatment energy levels. Specific etiologic factors and correlates of fatigue associated with radiation therapy have not been identified. Risk factors for persistent low energy in cancer patients include older age, advanced disease, and combination-modality therapy.
Fatigue is a dose-limiting toxicity of treatment with a variety of biotherapeutic agents. Biotherapy exposes patients with cancer to exogenous and endogenous cytokines. Biotherapy-related fatigue usually occurs as part of a constellation of symptoms called flulike syndrome. This syndrome includes fatigue, fever, chills, myalgias, headache, and malaise. Mental fatigue and cognitive deficits have also been identified as biotherapy side effects. The type of biotherapeutic agent used may influence the type and pattern of fatigue experienced.
Treatment with chemotherapy is a predictor of fatigue and can be exacerbated by the coexistence of pain, depression, and/or anxiety.[Level of evidence: II] A longitudinal, descriptive study reported highest levels of fatigue at the midpoint of a patient's chemotherapy cycles, with fatigue improving after treatment but not quite returning to baseline levels 30 days after the last treatment.
Evidence suggests that anemia may be a major factor in cancer-related fatigue (CRF) and quality of life in cancer patients.[27,28,29] Anemia can be related to the disease itself or caused by the therapy. Occasionally, anemia is simply a co-occurring medical finding that is related to neither the disease nor the therapy. Anemia is often a significant contributor to symptoms in persons with cancer. For individual patients, it can be difficult to discern the actual impact of anemia because there are often other problems that confound the ability to weigh the specific impact of anemia. The impact of anemia varies depending on factors such as the rapidity of onset, patient age, plasma-volume status, and the number and severity of comorbidities.
A retrospective review was conducted to understand the problem of anemia in patients receiving radiation therapy. Anemia was prevalent in 48% of the patients initially, and increased to 57% of the patients during therapy. It was more common in women than men (64% vs. 51%); however, men with prostate cancer experienced the greatest increase in anemia during radiation therapy. In certain cancers, such as cancer of the cervix and cancer of the head and neck, anemia has been found to be a predictor of poor survival and diminished quality of life in patients undergoing radiation therapy.[32,33,34,35]
Fatigue often occurs when the energy requirements of the body exceed the supply of energy sources.[36,37] In people with cancer, three major mechanisms may be involved: alteration in the body's ability to process nutrients efficiently, increase in the body's energy requirements, and decrease in intake of energy sources. Causes of nutritional alterations are listed in Table 1.