Cachexia is among the most debilitating and life-threatening aspects of cancer, and is more common in children and elderly patients.
Associated with anorexia, fat and muscle tissue wasting, psychological distress, and a lower quality of life, cachexia arises from a complex interaction between the cancer and the host. This process results from a failure of the adaptive feeding response seen in simple starvation and includes cytokine production, release of lipid-mobilizing and proteolysis-inducing factors, and alterations in intermediary metabolism.
Cytokines play a pivotal role in long-term inhibition of feeding by mimicking the hypothalamic effect of excessive negative feedback signaling from leptin, a hormone secreted by adipose tissue, which is an integral component of the homeostatic loop of body weight regulation. This could be done by persistent inhibition of feeding-stimulatory circuitry including neuropeptide Y. Cachexia should be suspected in patients with cancer if an involuntary weight loss of greater than five percent of premorbid weight occurs within a 3-6-month period. The two major options for pharmacological therapy have been either progestational agents or corticosteroids. However, knowledge of the mechanisms of cancer anorexia-cachexia syndrome has led to, and continues to lead to, effective therapeutic interventions for several aspects of the syndrome. These include antiserotonergic drugs, gastroprokinetic agents, branched-chain amino acids, eicosapentanoic acid, cannabinoids, melatonin, and thalidomide-all of which act on the feeding-regulatory circuitry to increase appetite and inhibit tumor-derived catabolic factors to antagonize tissue wasting and/or host cytokine release. The outcomes of drug studies in cancer cachexia should focus on the symptomatic and quality-of-life advantages rather than simply on nutritional end points, since the survival of cachexia cancer patients may be limited to weeks or months due to the incurable nature of the underlying malignancy. Communication among physicians and other health care professionals provides the patient with a multidisciplinary approach to care. The patient record will be an excellent resource to document a plan of care and patient responses to treatment. Psychological distress and psychiatric disorders are common among cancer patients. These problems are also as common among the family members of people with cancer. The use of psychological and behavioral interventions in cancer is increasing, and recent studies have suggested that some of these techniques may affect quality of life and, perhaps, survival rates. Evaluations of relaxation, hypnosis, and short-term group psychotherapy have suggested some benefit with regard to anorexia and fatigue, although the population most likely to benefit from these interventions has not yet been determined. Because weight loss shortens the survival time of cancer patients and decreases performance status, effective therapy would extend patient survival and improve quality of life.
Dept. of Social and Behavioral Medicine, Kagoshima University Graduate School of Medical and Dental Sciences, Japan.