Katie Arensmeyer, RN, MSN
The University of Pennsylvania School of Nursing
Ultima Vez Modificado: 17 de enero del 2012
Anorexia is the loss of appetite or inability to eat. Many cancer patients experience this prior to diagnosis and during treatment of the disease. Approximately 50% of patients with a new diagnosis of cancer have reported experiencing anorexia and unwanted weight loss (Adams et al., 2008). Weight loss is often the initial cause for the visit to the physician or clinic that then ultimately leads to the diagnosis of anorexia.
The loss of appetite in patients with cancer-related anorexia may be due to one or more of many causes. Cachexia is considered to be the involuntary weight loss of more than 10% of the original weight due to a metabolic disorder (Dahlin, Lynch, Szmuilowicz, & Jackson, 2006). Anorexia/cachexia syndrome is associated with weight loss and malnourishment, as often seen in late stage disease, and usually associated with poor prognosis and early death (Garcia & Polvino, 2007). Increased protein catabolism is thought to be a significant element of this syndrome.
Normal weight loss does not cause skeletal muscle wasting. In cancer-related anorexia, the weight loss targets muscle as well as fat and tissue. The result of this weight loss is cachexia, the loss of adipose tissue and lean muscle (Wood, Nail, Gilster, Winters, & Elsea, 2006). This muscle and fat loss is present in up to 80% of end stage cancer patients and may actually be the cause of death for some (Garcia & Polvino, 2007).
Anorexia and cachexia are so often seen together they are considered a syndrome that negatively impacts patient and family quality of life and prognosis. Anorexia/cachexia syndrome may result in increased anxiety to the patient and family because it is a visible sign of disease progression. Eating is often considered a social event. Social isolation may be a consequence of anorexia due to the inability of the patient to join and participate in the occasion. Anorexia may also negatively affect the patient due to religious, ethnic or cultural significance associated with eating (Dahlin et al., 2006).
A complex interaction of physiologic, gastrointestinal, metabolic, and nutritional factors as well as neuronal and endocrine mechanisms are attributed to anorexia and the loss of appetite. (Adams et al., 2008) Changes in any of these elements may result in anorexia, malnutrition and poor prognosis.
Cachexia is a hypercatabolic state associated with reduced muscle mass and loss of adipose tissue (Loprinzi & Jatoi, 2008). It is unclear whether anorexia causes cachexia or whether cachexia results in anorexia (Dahlin et al., 2006). Anorexia/cachexia syndrome appears to be due to the production of proinflammatory cytokines interleukin-1 Beta, tumor necrosis factor-alpha, and interleukin-6 as a result of an immune response by macrophage and other immune fighting cells (Wood et al., 2006). A principal feature in this syndrome is increased protein catabolism, which results in the muscle wasting element of cachexia (Loprinzi & Jatoi).
Loss of appetite is subjective and dependent on the patient’s view of appetite now and prior to the cancer diagnosis and treatment. Nutritional status and intake are also primarily subjective identifiers based on each patient and the retrospective reporting of intake. Objective markers for appetite and nutrition include serum albumin, weight loss and physical measurements. These markers, however, can be altered by ascites, edema and other factors that may modify the results (Dahlin et al., 2006).
Anorexia may be the result of taste changes, dysphagia, mucositis, early satiety, nausea and vomiting, constipation, side effects of medication, pain, dyspnea and psychological issues such as depression or anxiety (Dahlin et al., 2006). For the purposes of this paper, causes of anorexia will be limited to taste changes and early satiety, as these are often the result of cancer and treatment, regardless of the specific cancer diagnosis.
Dysgeusia is identified as taste changes or the perception of change in taste (Dahlin et al., 2006). When the four primary taste sensations (sweet, salty, sour and bitter) are disrupted, patients experience a decreased pleasure in eating. Cells secrete an amino acid-like substance that increases the sensation of bitter tastes. The patient with cancer may experience vitamin and mineral deficiencies, such as zinc, copper, nickel, and vitamin A, which may result in taste changes (Dahlin et al.).
Satiety is the sensation of fullness after eating. Mechanical, chemical and hormonal communication from the gut to the hypothalamus signal fullness. Disease or medications may result in premature signaling from the gut and early satiety (Dahlin et al., 2006). Early satiety causes a person to feel full before an appropriate amount of food or liquids have been ingested. This results in the inadequate intake of nutrition and subsequent malnutrition and weight loss.
There are several ways to address cancer-related anorexia without the use of pharmacological intervention. These methods are best when used prior to evidence of symptoms or cause. Addressing likely causes of anorexia such as decreased appetite, taste changes and early satiety before the patient experiences them may result in a more effective treatment.
The first step is nutritional counseling. Early recognition of the potential for nutritional compromise may benefit the patient and family by increasing quality of life and functional status (Dahlin et al., 2006). Dietary counseling has been shown to improve nutrition and help patients maintain weight (Adams et al., 2008).
According to the American Cancer Society (ACS), recommendations for nutrition and physical activity include nutritional counseling (National Guideline Clearinghouse [NGC], 2006). The ACS asserts that personal nutritional counseling for a short period of time can improve the appetite and nutritional intake resulting in decreased toxicities during cancer treatment. ACS recommendations include eating smaller meals more often during the day instead of the traditional three large meals and to avoid drinking any liquids with meals as this may give a sense of satiety that is not nutritional. Counseling may include the preparation of nutritional foods while taking into consideration the patient’s disease and comorbidities, ability to ingest and digest certain foods, symptom management, food preferences and any cultural or spiritual issues that may be relevant to the patient’s nutritional status (Adams et al., 2008). If the patient is not able to obtain proper nutrition from dietary intake of food, fortified and nutrient-dense beverages or foods should be added to the diet (NGC).
Taste changes that can result in anorexia may be managed if addressed when first recognized. Counseling the patient on different methods to mask the bitter tastes in the mouth may be beneficial to the patient. Such strategies include the control of odors from foods being prepared. The patient should have someone else prepare the food and only see or smell it when the food is ready to be consumed. Oral hygiene is very important to remove bad tastes from the mouth. The patient may find that sugar-free mints or gum will remove unpleasant tastes from the mouth and enable them to eat a normal diet (Dahlin et al., 2006).
Early satiety may be addressed by the use of metoclopramide (Reglan) to suppress gastroparesis due to disease or medications. Although metoclopramide is primarily used for nausea/vomiting in cancer patients, its use has been indicated in anorexia due to early satiety. To decrease early satiety a daily dose of 30 to 120mg PO, divided and taken prior to meals and bed, should be tried (Dahlin et al., 2006).
The most common pharmacological intervention is the use of appetite stimulants. There are currently three primary agents used to increase the appetite: corticosteroids, progestational agents and serotonin antagonists. These agents have not been proven to increase overall survival or quality of life. However, lack of appetite is psychologically and emotionally distressing to patients and care givers and appetite stimulants seem to relieve some of this distress. (Loprinzi & Jatoi, 2008)
Corticosteriods include dexamethasone, prednisolone and methylprednisolone. Corticosteroids are anti-inflammatory substances that are originally released by the adrenal gland. They cause fluctuations in metabolism and increase the appetite. The response is immediate but short lived. Patients begin to feel better, have increased appetite and energy. Patients on these agents are found to have an increased appetite but no apparent effect on weight gain (Loprinzi & Jatoi, 2008).
There are no clinical trials that have identified the most effective dose, frequency, route or type of corticosteroid to use. Subsequently, this is considered a short term solution due to the various adverse effects of corticosteroids such as myopathy, immunosuppression, congestive heart failure, insomnia, hyperglycemia, muscle wasting and weakness. Use of corticosteroids is recommended only for short term benefit or for patients with limited life expectancy. (Adams et al., 2008)
Progestational agents are synthetic analogues of progesterone. The most commonly used progestational agent is megestrol acetate (Megace). The exact mechanism of action in anorexia or cachexia is unknown. It has been studied and compared to corticosteroids, particularly dexamethasone. According to a randomized comparison conducted by Loprinzi, et al. (1999), appetite stimulation and weight gain was similar with megestrol acetate versus corticosteroids. There is less toxicity with megestrol acetate than corticosteroids. However, no difference between progestational agents and corticosteroids in overall survival or quality of life has been noted (Loprinzi & Jatoi, 2008).
Megestrol acetate does not have the toxicities experienced with corticosteroids. The primary adverse effect associated with Megace includes an enhanced risk of deep vein thrombosis, which is increased by the concurrent use of chemotherapy (Loprinzi & Jatoi, 2008). The dose range determined to be the most effective with least risk of toxicity is 400 to 800mg per day.
Cyproheptadine is a histamine and serotonin antagonist. In some observational studies it has been reported that patients with cancer related anorexia and cachexia have gained weight while on this medication (Loprinzi & Jatoi, 2008). The medication seems to have slight appetite stimulating affect. This is believed to be due to cyproheptadine counteracting the serotonin activity (Loprinzi & Jatoi, 2008). The accepted dose for weight gain is 8mg by mouth four times a day, starting with 2mg and increasing to 8mg over a three week period.
Several other therapies have been tried with limited success. Erythropoietin at varying doses given SQ showed no difference in food intake or weight gain (Adams et al., 2008). Cannabinoids have not shown any effects on anorexia in cancer patients in spite of their activity with advanced HIV patients (Loprinzi & Jatoi, 2008).
Ghrelin treatment has had positive results in preliminary studies on cancer related anorexia and cachexia (DeBoer et al., 2007). Ghrelin is an endogenous ligand for the GH secretagogue (GHS)-1a receptor and has been identified as the only known circulating orexigenic, or appetite stimulating, hormone (DeBoer et al.) Although studies have shown weight gain and appetite increase in rats, Ghrelin is only beginning to be studied in healthy humans (Garcia & Polvino, 2007). The potential is significant for management of anorexia and cachexia; however, the weight gain must be measured in lean body muscle and not water weight. Adverse effects have also not been identified at this point (DeBoer et al.).
Although there is no cure for cancer related anorexia, management of the symptom should begin with early counseling at initial disease diagnosis. Whether the cause of the anorexia is a symptom of the disease or a side effect of treatment it must be considered a serious matter both physically and psychologically. It is important for the healthcare provider to monitor weight changes, nutritional intake reports and assess the physical appearance of the patient. Reports from the family will also indicate whether the patient is receiving adequate nutrition to help with the treatment and prognosis.
Some of the primary interventions have been identified above. Anorexia/cachexia has been identified as an indicator of disease progression, poor prognosis and end of life. It is imperative that further studies be completed to help resolve the issues of nutrition and anorexia in cancer.
Anorexia/cachexia syndrome is extremely relevant to nursing due to the necessity for symptom management and patient care. Although cachexia is a very important symptom of cancer, as indicated earlier, anorexia may have a significant negative impact on the patient beyond the weight and muscle loss identified with cachexia. The loss of appetite can be very disturbing to the patient and family. Anorexia physiologically affects the patient and often results in decreased quality of life for the patient during treatment and at the end of life (Adams et al., 2008).
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