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Cachexia in Cancer Patients

© David Olle

Cachexia is the loss of body weight that occurs in a large number of cancer patients, and is mainly limited to the loss of fat and skeletal muscle. Cachexia has often been attributed to anorexia, which is the loss of appetite with a corresponding reduction in food intake. However, anorexia does not in itself explain the phenomenon, since attempts to increase food intake by nutritional supplementation or other means fail to reverse the progressive weight loss. Controlling cachexia is important to the outcome of the patient's cancer. Patients with weight loss live approximately half as long as those without, and those with greater weight loss live a shorter time than those with less or no weight loss.

Cachexia as a response of the body to the cancer tumor

Cachexia is not unique to cancer, but is seen in a variety of stress conditions, including infection, inflammation and tissue injury. These conditions result in an acute phase response, leading to increases in energy expenditures, and depletions of fat and skeletal muscle proteins. These alterations in metabolism provide a ready supply of nutrients for host defense and tissue repair. Although these metabolic changes are beneficial for short- term responses to infection or trauma, they can be detrimental to the long- term cancer patient.

In the case of cancer, the tumor secretes a number of substances that serve to increase the supply of nutrients for its own growth and development. Lipid mobilizing factor acts on adipose tissue to break down fat into fatty acids. Tumor necrosis factor and proteolysis-inducing factor act on skeletal muscle to break down protein into amino acids. 1 3 All of these breakdown products enter the liver where they are used for the production of glucose. The tumor then uses the glucose as an energy source. The breakdown products also stimulate the liver to produce acute phase proteins at the expense of skeletal muscle proteins. All of these processes are very energy consuming and result in an increased liver size. As part of the cachectic process, the body also normally secretes two forms of interleukin as well as interferon gamma. These substances are known as cytokines (as is tumor necrosis factor).

Treatment of cachexia

Improved nutrition

Although increased nutrient intake will not normally reverse the symptoms of cachexia by itself, it remains an important part in the overall treatment program. When the patient enters the clinic, his or her weight loss pattern, food intake, and factors that affect food intake should be assessed. 4 Symptoms that influence the patient's ability to eat must be managed. Foods of high caloric density should be encouraged, as well as nutritional supplements. If the patient's oral intake is insufficient, parenteral (intravenous administration) nutrition is commonly considered. However, a large number of studies have shown that this procedure is not beneficial in patient outcome, and may even be detrimental due to increased complications.