Abstract and Introduction
Cancer-related fatigue (CRF) is one of the most common symptoms reported by patients and is defined as the feeling of extraordinary exhaustion associated with a high level of distress, disproportionate to the patients' activity, and is not relieved by sleep or rest. Prevalence rates range from 59 to nearly 100% depending on the clinical status of the cancer. Except for chemotherapy-induced anemia, the mechanisms responsible for CRF are not yet completely understood. Therefore, CRF may be influenced by multiple possible somatic and psychosocial factors. CRF has been shown as either a short-term side effect of adjuvant cancer therapy or a chronic long-term late effect. Compared with other symptoms, such as pain or nausea, CRF is more distressing and often long lasting, with a strong impact on daily living and quality of life. The concept of fatigue has been widely elaborated and operationalized in different dimensions within the last few decades and specific instruments assessing fatigue in cancer populations have been developed. To support patients and alleviate CRF symptoms various treatment strategies are discussed in this article, including information and counseling, enhancement of activities, exercise and sports therapy, psychosocial interventions as well as pharmacological treatment. In most Western countries, treatment of CRF has been identified as a priority for advancing cancer patient care. This article gives an overview of the concept of CRF, its pathogenesis, assessment and treatment strategies.
Fatigue is described as a subjective sensation or an objective decrement of performance associated as a common symptom of various chronic diseases. With respect to cancer patients, cancer-related fatigue (CRF) is commonly defined as a self-recognized phenomenon that is subjective in nature and experienced as a feeling of tiredness or lack of energy that varies in degree, frequency and duration.[1,2] From the patient's point of view, fatigue is described as an unusual feeling of exhaustion, weakness or a loss of activity with sequels to emotional and cognitive functions.[1–3,101] Typically, CRF is not relieved by sleep or rest.
Investigations on CRF started in the 1970s primarily as a topic of psychological and nursing research. Since that time, numerous papers have been published showing an increased rate of publications, especially in the last two decades. Owing to the clinical significance of CRF, there has been a strong interest in developing assessment strategies and questionnaires in order to measure CRF problems as outcome or process criteria. Although CRF is not acknowledged as a disease (sensu International Classification of Disease [ICD] or Diagnostic and Statistical Manual of Mental Disorders classification), the Fatigue Coalition has proposed the criteria from ICD 10 for determining CRF and for describing the symptoms, causes and functional sequelae of CRF.
Fatigue as a clinical phenomenon is not a new concept. There have been research activities in the 19th and 20th Centuries. Since the early 1960s, ICD-classified diseases, such as chronic fatigue syndrome, neurasthenia or fibromyalgia, are discussed as primarily psychosomatic diseases that are interpreted as somatization disorders. CRF has to be distinguished from chronic fatigue syndrome and other fatigue syndromes, although there are some similarities with respect to phenomenology and theoretical explanation.
In cancer patients, fatigue is the most frequent symptom occurring during or after medical treatment, or also as a long-term late effect. Several epidemiological studies reveal prevalence rates ranging from 59 to 100%.[5,6] During the last decade, a considerable number of studies emphasize the complex problems faced by cancer patients who experience CRF while receiving treatment or afterwards. Furthermore, CRF can persist for many years once treatment has ceased,[8–10] whereas for patients with progressive disease, fatigue can be associated with an extremely limiting, or even loss, of overall quality of life. As a consequence, CRF has a serious impact on the quality of life of these patients and can affect their daily life, work, sexuality or family life.
Throughout the world new cancer treatments and approaches are investigated, mainly focusing on survival; however, it is important that health professionals continue to understand how CRF arises and how it affects the patient's quality of life. Although a lot of information and research findings on CRF have been provided within the last two decades, CRF is still under-reported, under-diagnosed and undertreated. Guidelines for assessment and treatment have been developed to improve recognition, assessment and treatment of CRF and enhance supportive care of patients.
Expert Rev Pharmacoeconomics Outcomes Res. 2011;11(4):441-446. © 2011 Expert Reviews Ltd.
Cite this: Cancer-related Fatigue - Medscape - Aug 01, 2011.