"Some Thoughts on Nutrition and Cancer Overview" GULF COAST VETERINARY ONCOLOGY'S TUMOR TIDBITS Volume 2, Number 4: March 2001 This Month's Feature: Some Thoughts on Nutrition and Cancer ______________________________________________ Tidbit Topic : SOME THOUGHTS ON NUTRITION AND CANCER OVERVIEW An inability to maintain nutritional status is a common problem for patients with cancer. The disease process and its treatment can lead to severe protein-calorie malnutrition, which is the single most common paraneoplastic syndrome or secondary diagnosis in the cancer patient. It is a major cause of morbidity and mortality. Protein-calorie malnutrition exists when the intake of acronutrients is inadequate to meet metabolic requirements. Progressive wasting, weakness, debilitation, compromised immune function, potential therapy intolerance, and ultimately death may result. DEFINITIONS -Anorexia, the loss of appetite or desire to eat, is the most common symptom in patients with cancer that may occur early in the disease process or later as the tumor grows and metastasizes. Anorexia is present in 15%-25% of all cancer patients at the time of diagnosis and is almost universal in patients with widely metastatic disease. Anorexia is the most common cause of decreased nutrient intake triggering malnutrition and progressive inanition (progressive deterioration with muscle wasting and body compositional change) in malignancy. -Cachexia is a clinical wasting syndrome evidenced by weakness and a marked and progressive loss of body weight, fat, and muscle. Anorexia and cachexia frequently occur together, but cachexia may occur in individuals who are ingesting adequate calories and protein but experience malabsorption of nutrients. It has been estimated that one half of all patients with cancer experience cachexia, two thirds while in a terminal phase of the disease. In addition, investigators have found no association between cachexia and tumor size, type, or extent. Cancer cachexia differs from simple starvation. Individuals adapt to starvation by decreasing their basal metabolic rate, whereas in cancer patients, the basal metabolic rate is not adaptive and may be increased, decreased, or normal. The pathogenesis is a complex mix of tumor, host, and treatment variables, which make this syndrome difficult to study. GENERAL EFFECTS OF THE TUMOR Many nutritional problems stem from a local tumor effect. Enlarging tumors in the gastrointestinal tract can cause obstruction, nausea and vomiting, impaired digestion, delayed transit, and malabsorption. Ovarian and genitourinary cancers may be associated with ascites leading to early satiety, progressive protein malnutrition especially with fluid loss at surgery or paracentesis), and fluid and electrolyte imbalances. Pain related to tumor bulk or location may be associated with severe anorexia and decreased oral intake. NUTRITIONAL EFFECTS OF THE TUMOR Marked alteration in normal metabolism of carbohydrate, protein, and lipid can occur. Tumor cells may derive significant energy from metabolism of glucose to lactate (Cori cycle) rather than from more complete oxidation of carbon dioxide and water (Krebs cycle). Additionally, conversion of lactate to glucose for gluconeogenesis by the liver consumes six ATP molecules per lactate-glucose cycle, producing energy-inefficient cycling. Tumor cells have an increased requirement for glucose as an energy source, either through altered enzymatic activity or due to relative hypoxia induced by poor tumor vascularization. Differences in the contribution of Cori cycle activity have been seen in patients who lose weight and in those with stable weight. Inhibition of phosphoenolpyruvate carboxykinase by hydrazine sulfate may decrease excess Cori cycle activity and improve glucose tolerance in cancer patients, but weight loss may not be reversed. Altered protein metabolism in patients with cancer may stem from increased uptake of amino acids by the tumor cells compared with that of normal cells, decreased protein synthesis, increased protein degradation, and protein loss through fistulas or by gastrointestinal losses. In addition, decreased intake secondary to anorexia, when need is increased or normal, is often the basis of negative nitrogen balance. Altered lipid metabolism can occur as a result of mobilization and the use of fatty acids as an additional energy source when the glucose supply of the body is exhausted by the tumor. A decrease in fat mobilization has also been observed. Mediators of primary cachexia (i.e., cachexia without a mechanical or function etiology) can include substances with hormone-like characteristics or products of host tissues that influence metabolism indirectly. The latter include a number of cytokines such as tumor necrosis factor (TNF-alpha), interleukin-6, and gamma-interferon. Additionally, lipid mobilizing factors have also been implicated. Lack of enteral stimulation may increase levels of circulating cytokines. In addition to alterations in carbohydrate, protein, and lipid metabolism, cancer cells produce peptides, oligonucleotides, and other metabolites that may be responsible for the genesis of anorexia and cachexia. Tumor-produced substances may alter the sense of taste, leading to an aversion to meat and a decreased taste sensation. Tumors can also produce hormone substances, similar to those seen in paraneoplastic syndromes, which can alter nutrient intake, absorption, and metabolism. NEUROLOGIC EFFECTS OF THE TUMOR -Tumors may cause anorexia through a peripheral effect on neuroendocrine cells or neuroreceptors and through a direct effect on hypothalamic and other central nervous system peptidergic and responder cells. -Early satiety or a sense of fullness is a frequent symptom in anorectic cancer patients, suggesting the importance of inhibitory signals from the gastrointestinal tract in limiting their food intake. -Central nervous system tumors that cause confusion or somnolence may affect nutritional status because lack of attention may lead to decreased intake. EFFECT OF CANCER THERAPIES Cancer therapies and their side effects can also greatly contribute to progressive nutritional deterioration. The therapy may have a direct effect, such as protein and fat malabsorption after a gastrectomy or pancreatectomy, or indirect effects, such as increases in metabolic demands caused by infection or a neutropenic febrile reaction (there is an increased caloric need of approximately 10%-13% per degree above 37 degrees Celsius). -Surgery: Difficulty in chewing and swallowing. Stasis, protein and fat malabsorption, vitamin and mineral deficiencies, diarrhea, and excessive fluid and electrolyte losses. Vitamin and mineral deficiencies, diabetes mellitus. Surgery involving the urinary tract can lead to acid-base imbalances and electrolyte abnormalities. Additionally, complications of surgery with nutritional implications may include infection, fistulae (internal or enterocutaneous), and short-bowel syndrome. Patients may actively decrease their oral intake after a diverting or end colostomy to decrease the ostomy output. This should be addressed in any patient with a marked decrease in oral intake after such surgery. -Chemotherapy: Chemotherapy can cause anorexia, nausea and/or vomiting, diarrhea or constipation, stomatitis/mucositis, taste alterations or aversions, and infectious complications. Symptoms that have an impact on nutrition and that last longer than 2 weeks are especially significant. The frequency and severity of these side effects depend on the class of drug, the dose, the drug combination, and whether the chemotherapy is part of a combined modality program. Nutritional status may be strongly affected with prolonged treatment of febrile neutropenia where metabolic needs may increase 25% with a temperature of 39 degrees Celsius. -Radiation therapy: Radiation therapy is associated with both acute and late sequelae that affect nutritional status. Head and neck area: anorexia, taste alterations or aversions, dry mouth, mucositis, gingivitis, dysphagia, trismus, dental caries, and abscess formation. Thoracic irradiation: esophagitis (radiation-induced esophageal mucositis, candidiasis, or viral infections), dysphagia, esophageal reflux, and nausea and vomiting. Diarrhea, nausea and vomiting, enteritis, proctitis, or fistula formation are possible side effects caused by abdominal or pelvic irradiation. Fatigue, which may result in decreased appetite and motivation to eat. Late sequelae: strictures, enteritis, malabsorption, or gastrointestinal obstruction. -Immunotherapy: Immunotherapy (e.g., biologic response modifiers) may be associated with fever, fatigue, and weakness, which can lead to decreased appetite and increased need for protein and calories. Febrile reactions are associated with an approximate 10% increase in metabolic requirements per degree above 37 degrees Celsius. NUTRITIONAL ASSESSMENT - HISTORY Weight history (current, usual, and ideal); assessment of oral intake changes (type and duration); symptoms impacting on nutrition (including anorexia, nausea and vomiting, diarrhea, constipation, stomatitis/mucositis, dry mouth/olfactory abnormalities, and pain); medications that may affect intake or metabolic requirements; other medical conditions that may affect nutritional intake or nutrition intervention options; and performance status evaluation. The client should be asked about changes in intake compared with what is normal for their pet and the duration of the change if present. Useful data also include specific likes, dislikes, and intolerances of the pet with cancer; may help to determine the need for specific supplemental enzymes (lactase, other disaccharidases, or pancreatic enzymes). NUTRITIONAL ASSESSMENT - EXAMINATION Physical examination entails a general assessment of physical condition, including evidence of weight loss, loss of subcutaneous fat, muscle wasting, presence of sacral or tibial edema, or ascites. Clinical palpation of the triceps muscle can often provide an excellent estimate of nutrition, since extensors tend to lose muscle faster than flexors. This method of nutritional assessment is limited by both the technique and interobserver variability. Laboratory evaluations that may contribute to nutritional evaluation or appropriate nutritional intervention include assessment of visceral protein status (serum transferrin or albumin), renal and liver function, pancreatic endocrine function (glucose), serum electrolytes and minerals (calcium, magnesium, and phosphorus), and hematologic evaluation (total lymphocyte count and red cell indices). GENERAL MANAGEMENT GUIDELINES The aim of nutritional intervention is to minimize the degree of negative nitrogen balance (i.e., excessive loss of body protein not compensated by adequate nutritional intake). Options for supportive nutritional care of the pet with cancer are determined by one or more of the following: the presence of a functional gastrointestinal tract; type of therapy (independent of palliative or curative intent), i.e., site and extent of surgical resection, specific type of chemotherapy, site and size of radiation field, use of biologic response modifiers, or multimodality therapy ;quality of life, performance status, or prognosis. Maintenance of body composition and adequate nutritional status can help patients with cancer feel and look better and may also help them tolerate therapy. Problems caused by local tumor effects may subside when the tumor responds to therapy. MANAGING ANOREXIA A major cause of anorexia in patients with cancer is food odor. Patients suffering from anorexia should not be in a room where the odors of food preparation can be detected. Foods with reduced odors are preferable for patients/pets with cancer. Suggestions for helping patients with cancer manage anorexia include the following: 1. Eat small frequent meals (every 1-2 hours by the clock). 2. Eat food (including snacks) that is caloric- and protein-dense. 3. Avoid foods low in calories and protein and avoid empty calories (i.e., food without protein and micronutrients, such as soda). 4. Avoid liquids with meals (unless used sparingly to improve dry mouth or dysphagia) to decrease problem of early satiety. 5. Add extra calories and protein to food (e.g., butter, skim milk powder, honey, brown sugar). 6. Take medications with high-calorie fluids (e.g., commercial nutritional supplement) unless the medication must be taken on an empty stomach. 7. Experiment with recipes, flavorings, spices, types and consistencies of food. This is important since food preferences may change from day to day. 8. Avoid strong aromas if they are bothersome. Strategies include the use of boiling bags, cooking outdoors on a grill, the use of kitchen fan when cooking, serving cold plates rather than hot foods (since odors come from the rising steam). Suggestions for helping patients with cancer manage taste changes include the following: 1. Substitute poultry, fish, eggs, and cheese for red meat. 2. Marinate meats with sweet marinades or sauces. 3. Serve meats chilled rather than hot. 4. Use extra seasonings, spices, and flavorings, but avoid flavorings that are very sweet or very bitter. An elevated threshold for taste may make food taste bland or boring. 5. Use lemon-flavored drinks to stimulate saliva and taste, but avoid artificial lemon and use sweeteners sparingly. Suggestions for lessening or alleviating either dry mouth or dysphagia include the following: 1. Eat soft or moist foods. 2. Process foods in blender. 3. Lubricate foods with creams, gravies, or oils. 4. Avoid rough, irritating foods. 5. Avoid hot or cold foods. 6. Avoid foods that adhere to the roof of the mouth. Nutritional support: pharmacological approaches Pharmacologic intervention to increase oral nutritional intake can range from pain management to treatment of constipation or diarrhea, the use of gastric prokinetic agents, and the use of specific orexigenic agents (appetite stimulants). This may include the use of Cyproheptadine, Stanazolol, Prednisone. ___________________________________________________________________ For further information on "Nutrition and Cancer" or about any other cancer issue, please call us (713-693-1166) or email Dr. Hahn at drhahn@g... . For more information on the web, use Medline at: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi