One of the most vexing complications of living with cancer is cancer-related fatigue (CRF). Clinicians are well aware that patients experience the problem during treatment and as their disease advances; in addition, many have continued problems with fatigue even when treatment has ended and they are cancer-free.
WHAT IS CRF?
CRF has various definitions. According to the National Comprehensive Cancer Network’s clinical practice guideline, cancer fatigue is “a persistent, subjective sense of tiredness … related to cancer or cancer treatment that … interferes with usual functioning.”1 Other experts write that “fatigue is a subjective, unpleasant symptom which incorporates total body feelings ranging from tiredness to exhaustion, creating an unrelenting overall condition which interferes with individuals’ ability to function to their normal capacity.”2
Although a single, clear definition of CRF is lacking, patients with cancer have agreed that when compared with the normal fatigue of daily living, the fatigue related to their illness had a faster onset and was more intense in every way; they had not expected that it would drain their energy so thoroughly or last so long. Some patients are not able to work as a result, while others cannot even perform activities of daily living. A National Cancer Institute PDQ document notes in the section on posttreatment cancer fatigue that although few studies have been done on fatigue in cancer survivors, their experience seems to be similar to the experience of patients with chronic fatigue syndrome in the general medical setting.3
In writing about a recent study of fatigue among survivors of breast cancer, researchers suggest that even though “fatigue is the symptom reported most commonly by breast cancer survivors, its significance or even presence has been [underrecognized] and [underappreciated] by health care providers.”4 In their work on CRF and sleep, the authors note that the quality of sleep is as important as the quantity of sleep and that when the quality of sleep is poor, the patient is likely to experience severe CRF. They also found that younger women complained of more severe fatigue than older women did, possibly because younger patients may have more severe (and debilitating) illness that requires more aggressive (and debilitating) treatment. Also, when older women experience CRF, it may not impact their lives as significantly as it does the lives of younger, more active women.4
A COMPLEX ETIOLOGY
Fatigue in cancer patients and cancer survivors may have physical or psychological causes. Anxiety and depression sap energy, as can the medications used to alleviate these conditions—a complexity that presents clinicians with a treatment challenge. The very fact of having had cancer may cause depression and anxiety, and effective medications are available to help patients cope with these understandable emotional states. However, the antidepressant and anxiolytic drugs prescribed for treatment are often soporific or enervating. Thus the patient may feel better psychologically but may still feel tired or fatigued—just from a different source.
In one study of 160 patients who had various types of cancer at different stages—primary local disease, local recurrence, and metastatic disease—76.3% reported moderate or severe CRF.5 The researchers found that “anxiety, depression, and dimensions of quality of life were significantly related with CRF.”5 Importantly, these patients considered their fatigue to be a side effect of treatment, and they hesitated to report what they were feeling because they did not want their treatment to be changed to a less aggressive regimen.5
Pathophysiologic reasons for CRF can be as common as the anemia that results from bone marrow involvement or as rare as the proliferation of malignant plasma cells in multiple myeloma. One group studied patients with cancers of the digestive system and found that those with pancreatic cancer experienced a higher rate of depression than those with liver, esophageal, gastric, or colorectal cancer.6 Furthermore, depression, fatigue, pain, and loss of appetite among patients with pancreatic cancer were more severe than in the patients with other types of digestive system malignancies.6
Finally, nutritional deficiencies often lead to CRF. Although eating properly can be a challenge for someone who is in pain or experiencing the side effects of chemotherapy, such patients need enough calories, fluids, protein, and other nutrients to decrease fatigue and increase energy. Unfortunately, antiemetics, antihistamines, and narcotics can cause loss of appetite, fatigue, weakness, and sometimes insomnia.
Fortunately, CRF is becoming more recognized and legitimized, an important step in helping patients through their illness. A thorough investigation for underlying causes is essential, whether the patient is in active treatment for cancer or is a cancer survivor. ONA
Bette Kaplan is a medical writer in Tenafly, New Jersey.
1. National Comprehensive Cancer Network. Cancer-related fatigue. Clinical practice guidelines in oncology. J Natl Compr Canc Netw. 2003;1(3):308-331.
2. Ream E, Richardson A. Fatigue: a concept analysis. Int J Nurs Stud. 1996;33(5):519-529.
3. Fatigue (PDQ). National Cancer Institute Web site. http://www.cancer.gov/cancertopics/pdq/supportivecare/fatigue/healthprofessional/allpages#Section_104. Updated March 12, 2010. Accessed May 5, 2010.
4. Banthia R, Malcarne VL, Ko CM, et al. Fatigued breast cancer survivors: the role of sleep quality, depressed mood, stage and age. Psychol Health. 2009;24(8):965-980.
5. Luthy C, Cedraschi C, Pugliesi A, et al. Patients’ views about causes and preferences for the management of cancer-related fatigue—a case for non-congruence with the physicians? [published online ahead of print February 19, 2010]. Support Care Cancer.
6. Jia L, Jiang SM, Shang YY, et al. Investigation of the incidence of pancreatic cancer-related depression and its relationship with the quality of life of patients. Digestion. 2010;82(1):4-9.