Nutrition support in patients with cancer: what do the data really show?

Glutamine supplementation in bone marrow transplantation

An increasing number of clinical investigations have focused on supplementation of specialized enteral and parenteral nutrition with the amino acid glutamine. This interest derives from strong evidence in animal models and emerging clinical data on the efficacy of glutamine administration following chemotherapy, trauma, sepsis and other catabolic conditions. Glutamine has protein-anabolic effects in stressed patients and, among many key metabolic functions, is used as a major fuel/substrate by cells of the gastrointestinal epithelium and the immune system. These effects may be particularly advantageous in patients undergoing bone marrow transplantation (BMT), who exhibit post-transplant body protein wasting, gut mucosal injury and immunodeficiency. Studies to date indicate that enteral and parenteral glutamine supplementation is well tolerated and potentially efficacious after high-dose chemotherapy or BMT for cancer treatment. Although not all studies demonstrate benefits, sufficient positive data have been published to suggest that this nutrient should be considered as adjunctive metabolic support of some individuals undergoing marrow transplant. However, BMT is a rapidly evolving clinical procedure with regard to the conditioning and supportive protocols utilized. Thus, additional randomized, double-blind, controlled clinical trials are indicated to define the efficacy of glutamine with current BMT regimens.

Enteral compared with parenteral nutrition: a meta-analysis

BACKGROUND

The difference in outcomes in patients is unclear when 2 types of enteral nutrition, ie, tube feeding and conventional oral diets with intravenous dextrose (standard care), are compared with parenteral nutrition.

OBJECTIVE

We reviewed systematically and aggregated statistically the results of prospective randomized clinical trials (PRCTs) to examine the relations among the nutrition interventions, complications, and mortality rates.

DESIGN

We conducted a MEDLINE search for PRCTs comparing the effects of enteral and parenteral nutrition in adults. Two different people abstracted data for the method and outcomes separately. We used fixed-effects meta-analysis technique to combine the relative risks (RRs) of the outcomes of infection, nutrition support complications, other complications, and mortality.

RESULTS

Twenty-seven studies in 1828 patients met the study criteria. Aggregated results showed a significantly lower RR of infection with tube feeding (0.64; 95% CI: 0.54, 0.76) and standard care (0.77; 95% CI: 0.65, 0.91). A priori hypotheses showed a lower RR of infection with tube feeding than with parenteral nutrition, regardless of nutritional status, presence of cancer, year of study publication, or quality of the study method. In studies in which participants had high rates of protein-energy malnutrition, there was a significantly higher risk of mortality (3.0; 95% CI: 10.9, 8.56) and a trend toward a higher risk of infection with standard care than with parenteral nutrition (1.17; 95% CI: 0.88, 1.56).

CONCLUSIONS

Tube feeding and standard care are associated with a lower risk of infection than is parenteral nutrition; however, mortality is higher and the risk of infection tends to be higher with standard care than with parenteral nutrition in malnourished populations.

Glutamine supplementation in cancer patients receiving bone marrow transplantation and high dose chemotherapy

Glutamine supplementation of enteral and parenteral nutrition support has received increased attention in the research community over the past decade. Glutamine may become a conditionally essential nutrient during certain catabolic states, including after bone marrow transplantation (BMT). The administration of enteral or parenteral glutamine seems safe and also potentially efficacious in some patient groups undergoing intensive treatment for cancer. Studies indicate that adjunctive glutamine treatment may improve nitrogen retention, decrease clinical infection and length of hospital stay and reduce the incidence and severity of mucositis after BMT and high dose chemotherapy. Although not all studies demonstrate benefit, there are sufficient positive data to suggest that this nutrient should be considered in the metabolic support of many individuals undergoing the catabolic process of marrow transplantation. Given the available data, randomized, double-blind, controlled clinical trials of glutamine-enriched nutrition in patients receiving BMT and high dose chemotherapy protocols are indicated to further define the utility of this amino acid as adjunctive therapy. Studies of glutamine nutrition combined with current combinations of cytoreductive agents and hematopoietic growth factors in BMT will be particularly pertinent.

Using research to change practice: enteral feedings for pediatric oncology patients

This report details a study whose purpose was to show the safety of and describe the clinical and financial outcomes of nasogastric (NG) and nasojejeunal (NJ) tube feedings for nutritional support during and after intensive treatment for cancer. During a 17-month period, NG or NJ tubes were inserted in 25 patients who experienced, or were anticipated to experience, suboptimal nutrition during or after their chemotherapy (n = 14), radiation therapy (n = 2), or chemotherapy plus radiation (n = 5), after bone marrow transplant (n = 2), and as a result of neurological impairment (n = 2). Patient ages ranged from 1 month to 14 years. NG/NJ tubes were used for a total of 1415 patient days (median 40 days). Of those, 756 days occurred in the hospital (median, 18 days) and 659 were outpatient days (median = 12 days). Total parenteral nutrition (TPN) was used during 104 patient days (range, 1 to 35 days), and combination NG/NJ feedings were given with TPN for a total of 101 days. A comparable number of days of TPN therapy for the NG-fed patients would have cost $177,390 (average $135/day), compared with $65,700 (average, $50/day) for enteral feedings, for a savings of $111,690. Ten patients experienced grade 2 to 3 diarrhea and/or vomiting during the study. No untoward outcomes were identified. Enteral feedings were found to be a safe and cost-effective method for providing nutrition to these children with cancer.

Nutritional support in critically ill patients with cancer

Nutritional depletion is a common problem seen in critically ill patients with cancer and is associated with increased morbidity and mortality. Infection and injury activate a cascade of metabolic events that leads to a poor nutritional state and wasteful energy consumption. The goals of nutritional support entail minimizing starvation, preventing nutrient deficiencies, supporting or improving immune function, and facilitating tissue repair and wound healing. Further understanding of the metabolic changes of illness will improve effective regulation of the inflammatory events occurring in critically ill patients. Multiple clinical parameters are available to assess the nutritional status in critically ill patients, but no standard recommendations can be made at this time. The use of these parameters can be appropriate, provided that their limitations are understood clearly. The development and standardization of objective parameters to identify patients at risk or with subclinical malnutrition are needed. Enteral and parenteral feedings are safe and effective methods to deliver nutrients to critically ill patients with cancer who are unable to ingest adequate amounts orally. Early nutritional support should be instituted in the appropriate clinical setting. Specialized nutritional solutions and supplements require careful consideration in patients with renal, hepatic, cardiac, or pulmonary disorders. The unselective use of nutritional support is not indicated in well-nourished patients with cancer undergoing surgery, chemotherapy, or radiotherapy in whom adequate oral intake is anticipated. Nutritional support remains an important adjunctive therapy in the overall management of critically ill patients. Continued clinical investigations in nutrition are necessary to identify other groups of patients who can benefit from nutritional interventions.

Terminal nutrition: framing the debate for the withdrawal of nutritional support in terminally ill patients

Nutrition and hydration have long been considered to be life-sustaining therapies that are associated with comfort and relief of suffering. This belief is largely based on our own experiences with the sensations of thirst and hunger, which have led physicians to question whether withdrawing or withholding nutritional support from a dying patient can be morally or ethically justified. When considered in light of the available evidence, the underlying premise of this question must be reevaluated. The evidence suggests an alternative formulation, namely, that unrequested nutritional support provided by either the enteral or parenteral route to a terminally ill patient may be both medically and ethically indefensible because it may increase suffering without improving outcome.

Cachexia and asthenia in cancer patients

Over the past 10 years, there have been major advances in the understanding of cancer cachexia and asthenia. These common complications of cancer are now thought to be the consequences of complex interactions between host, tumour, and psychosocial factors. Cachexia and asthenia commonly coexist, but they can occur independently of each other. Recently identified tumour-derived factors cause lipolysis and protein catabolism. Cytokines produced by the host in response to tumour presence cause metabolic abnormalities, which result in decreased protein and lipid synthesis, increased lipolysis, and anorexia. Many other factors contribute to asthenia, such as anaemia, autonomic failure, and muscular abnormalities. Future research should clarify optimum management. The way forward seems to lie in a multidimensional approach with combined therapy to manage both cancer cachexia and asthenia.

Evidence base for specialized nutrition support

Data regarding the use of both parenteral and enteral specialized nutritional support (SNS) are available for a variety of common clinical scenarios. Herein, the data are reviewed for SNS in the context of critical illness, perioperative care, wasting syndromes (including HIV disease and cancer), and gastrointestinal disease (including short bowel syndrome, inflammatory bowel disease, and pancreatitis).

Plasma antioxidant status after high-dose chemotherapy: a randomized trial of parenteral nutrition in bone marrow transplantation patients

BACKGROUND

Chemotherapy and radiation therapy result in increased free radical formation and depletion of tissue antioxidants. It is not known whether parenteral nutrition (PN) administered during bone marrow transplantation (BMT) supports systemic antioxidant status.

OBJECTIVE

The aims of the study were to determine 1) whether high-dose chemotherapy decreases concentrations of major circulating antioxidants in patients undergoing BMT and 2) whether administration of standard PN maintains systemic antioxidant concentrations compared with PN containing micronutrients and minimal lipids alone.

DESIGN

Twenty-four BMT patients were randomly assigned to receive either standard PN containing conventional amounts of dextrose, amino acids, micronutrients, and lipid (120 kJ/d) or a solution containing only micronutrients (identical to those in standard PN) and a small amount of lipid (12 kJ/d). Plasma antioxidant status was measured before conditioning therapy and serially at days 1, 3, 7, 10, and 14 after BMT.

RESULTS

Plasma glutathione (GSH) and alpha- and gamma-tocopherol concentrations decreased and the GSH redox state became more oxidized after conditioning chemotherapy. Plasma cysteine concentrations were unchanged, whereas cystine concentrations increased. Plasma vitamin C and zinc concentrations and GSH peroxidase activity increased over time. Plasma alpha-tocopherol concentrations were lower in patients given standard PN. There were no differences in other plasma antioxidants between groups.

CONCLUSIONS

A significant decline in GSH-glutathione disulfide, cysteine-cystine, and vitamin E status occurs after chemotherapy and BMT. Standard PN does not improve antioxidant status compared with administration of micronutrients alone. Further evaluation of PN formulations to support patients undergoing high-dose chemotherapy and BMT are needed.

Nutritional support of the cancer patient: issues and dilemmas

Malnutrition in cancer patients results from multifactorial events and is associated with an alteration of quality of life and a reduced survival. A simple nutritional assessment program and early counselling by a dietitian are essential to guide nutritional support and to alert the physician to the need for enteral (EN) or parenteral nutrition (PN). A daily intake of 20-35 kcal/kg, with a balanced contribution of glucose and lipids, and of 0.2-0.35 g nitrogen/kg is recommended both for EN and PN, with an adequate provision of electrolytes, trace elements and vitamins. EN, always preferable for patients with an intact digestive tract, and PN are both safe and effective methods of administering nutrients. The general results in clinical practice suggest no tumor growth during nutritional support. The indiscriminate use of conventional EN and PN is not indicated in well-nourished cancer patients or in patients with mild malnutrition. EN or PN is not clinically efficacious for patients treated with chemotherapy or radiotherapy, unless there are prolonged periods of GI toxicity, as in the case of bone marrow transplant patients. Severely malnourished cancer patients undergoing major visceral surgery may benefit from perioperative nutritional support, preferably via enteral access. Nutritional support in palliative care should be based on the potential risks and benefits of EN and PN, and on the patient's and family's wishes. Research is currently directed toward the impact of nutritional pharmacology on the clinical outcome of cancer patients. Glutamine-supplemented PN is probably beneficial in bone marrow transplant patients. Immune diets are likely to reduce the rate of infectious complications and the length of hospital stay after GI surgery. Further studies are needed to determine the efficacy of such novel approaches in specific populations of cancer patients, and should also address the question of the overall cost-benefit ratio of nutritional pharmacology, and the effect of nutritional support on length and quality of life.

Nutrition support in cancer

OBJECTIVES

To describe nutrition intervention strategies frequently used to support cancer patients experiencing malnutrition.

DATA SOURCES

Textbook chapters, database reports, and current related literature.

CONCLUSIONS

Clinicians have many options for providing nutrition support interventions for the cancer patient at risk for malnutrition. The most appropriate strategy for a patient should be based on a careful assessment of contributing factors with input from a multidisciplinary team.

IMPLICATIONS FOR NURSING PRACTICE

It is important for nurses to be knowledgeable about nutrition intervention options available to patients at various points along the cancer trajectory. Oncology nurses are in a key position to provide support to patients and families with regard to nutrition issues. Of paramount importance is their contribution to ongoing assessment of nutritional status and early and aggressive intervention to meet nutritional needs.

Nutritional issues in patients with severe neutropenia

OBJECTIVES

To provide information on the assessment and management of the nutritional needs of patients with severe neutropenia.

DATA SOURCES

Textbook chapters, research articles, and review articles.

CONCLUSIONS

Malnutrition is a common result of high-dose chemotherapy treatment. Clinical outcomes are directly related to careful assessment, early intervention, and ongoing evaluation and monitoring in the severely neutropenic population.

IMPLICATIONS FOR NURSING PRACTICE

Early assessment, management, and psychological support are essential in meeting the needs of this patient population.

Use of TPN in terminally ill cancer patients

Total parenteral nutrition (TPN) is often used as an adjunct to cancer therapy. However, it is increasingly being used in terminally ill cancer patients without clearly defined reasons. To determine the validity of the use of TPN in terminally ill cancer patients, 26 patients with limited life expectancy due to end-stage cancer were given TPN by their physicians, and the validity of its use was evaluated using the criteria of 1) quality of life, and 2) ultimate outcome. Patients were divided into two groups according to the use of TPN. Group I = TPN as adjunct of medical therapy, n = 15 (eight male, seven female), mean age 32 y. Group II = TPN for in-hospital supportive care, n = 11 (two male, nine female), mean age 56 y. Nutritional status on admission, quality of life (assessed by extent of daily activities, pain, and ability to sustain oral intake), and ultimate treatment outcome were determined. Mean weight loss in patients in Group I was 8.6 kg, 11 patients out of 15 were malnourished; mean weight loss in patients in Group II was 21 kg, and all of the 11 patients belonging to this group were malnourished. Two patients of Group I improved their quality of life, while 6 declined and 7 died; in Group II, 3 improved their quality of life, 4 declined, and 4 died. We conclude that when TPN was given either as an adjunct to in-hospital aggressive therapy for cancer or for in-hospital supportive care, quality of life did not improve in the majority of patients; nor did it influence ultimate outcome. These objective data, thus, raise the question of the validity of the use of TPN in terminally ill cancer patients. However, barring the cost factor, it is recognized that subjective reasons for giving TPN to terminally ill cancer patients persist and include compassionate, ethical, religious, or emotional reasons.

Nasogastric tube feedings in children with high-risk cancer: a pilot study

PURPOSE

To avoid the cost and complications of total parenteral nutrition (TPN), this study was initiated to determine the feasibility of administrating nasogastric tube feedings in children receiving intensive chemotherapy (CTX) or bone marrow transplantation (BMT).

PATIENTS AND METHODS

Seventeen children (aged 2 to 19 years) were entered into the study. Continuous nasogastric feedings of a glutamine-supplemented elemental diet were administered during CTX and at the time of rehospitalization for fever, neutropenia, and mucositis.

RESULTS

Fourteen children were treated with CTX and 3 with BMT. Enteral tube feedings were administered for 216 days; each patient received a mean of 12.7 days. The tubes were generally well tolerated, and there were no instances of sinusitis or epistaxis. Six children received TPN in addition to enteral feedings. The hospital charges for the enteral feedings were $25,348, compared to $112,299 for the same number of days of TPN.

CONCLUSIONS

Nasogastric tube insertion and enteral tube feedings in children receiving intensive CTX or BMT can be accomplished with minimal complications and significant cost savings when compared to TPN.

Enteral nutrition in wasting disorders

Cachexia, weight loss, and malnutrition are found commonly in patients with gastrointestinal tract cancer and in patients with human immunodeficiency virus. This wasting has been linked not only to survival, but also to alterations in host defenses, functional ability, and quality of life in these patients. Enteral nutritional support has been provided to these patients with the goal of preventing or correcting malnutrition in an attempt to improve measures of mortality, morbidity, and quality of life. Studies presented in this review have examined the impact of the timing, the composition, and the route of nutritional support on these outcome variables to evaluate the use of enteral nutritional support in these wasting disorders. There remains a paucity of strong clinical evidence that supports any improvements in outcome variables associated with the provision of enteral nutritional support in these patients.

Metabolic alteration in patients with cancer: nutritional implications

During the past 20 years, efforts have been made to elucidate the metabolic changes observed in patients with cancer by using stable and radioactive isotopic tracers. These metabolic changes in patients with cancer may be similar to those in other stress conditions, in which glucose production and utilization, lipolysis and free fatty acid flux, and net protein catabolism are increased. Stress hormones, such as glucagon and catecholamines, and certain cytokines may be responsible for these metabolic changes. Although it has been shown that cachexia in patients with cancer signals a poor prognosis, efforts to improve the clinical outcomes with nutritional support have been disappointing. The failure of cancer patients to respond to nutritional support may be related to an alteration in the intermediate metabolism. Therefore, further research evaluating the metabolic abnormalities associated with cancer may lead to more effective nutritional therapies.

Why do patients with weight loss have a worse outcome when undergoing chemotherapy for gastrointestinal malignancies?

The aim of this study was to examine whether weight loss at presentation, in patients who were to receive chemotherapy for gastrointestinal carcinomas, influences outcome and whether nutritional intervention would be worthwhile. This study was a retrospective review of prospectively gathered data. The outcomes of patients with or without weight loss and treated for locally advanced or metastatic tumours of the oesophagus, stomach, pancreas, colon or rectum were compared. In 1555 such consecutive patients treated over a 6-year period, weight loss at presentation was reported more commonly by men than women (51 versus 44%, P = 0.01). Although patients with weight loss received lower chemotherapy doses initially, they developed more frequent and more severe dose limiting toxicity--specifically plantar-palmar syndrome (P < 0.0001) and stomatitis (P < 0.0001)--than patients without weight loss. Consequently, patients with weight loss on average received 1 month (18%) less treatment (P < 0.0001). Weight loss correlated with shorter failure-free (P < 0.0001, hazard ratio = 1.25) and overall survival (P < 0.0001, hazard ratio = 1.63), decreased response (P = 0.006), quality of life (P < 0.0001) and performance status (P < 0.0001). Patients who stopped losing weight had better overall survival (P = 0.0004). Weight loss at presentation was an independent prognostic variable (hazard ratio = 1.43). The poorer outcome from treatment in patients with weight loss appears to occur because they receive significantly less chemotherapy and develop more toxicity rather than any specifically reduced tumour responsiveness to treatment. These findings provide a rationale for attempting randomised nutritional intervention studies in these patients.

Perioperative nutrition: parenteral versus enteral

Malnutrition has been shown to have an adverse effect on the clinical outcome of surgical patients. During the past 25 years, investigators have sought to determine whether clinical outcome can be improved by the administration of pre- or postoperative (perioperative) nutritional support. We conclude that the clinical outcome of severely malnourished surgical patients is improved by perioperative nutritional support and that this should be administered whenever possible via the enteral route. The clinical outcome of less severely malnourished surgical patients, including those who are normally nourished, can be improved by the administration of oral dietary supplements at a time in the postoperative period when patients are ingesting free fluids. Some of these patients may also benefit from early postoperative enteral tube feeding, but further work is required to determine the effects following different types of surgery before this is adopted for routine use. Parenteral nutrition is only indicated in the postoperative period when major complications occur in association with intestinal failure.

Nutritional support of the hospitalized patient

Comprehensive care of patients in hospitals includes assessment of nutritional status and provision of appropriate support. This approach is facilitated by knowledge of the essential differences in metabolism between starved and stressed states. Nutritional assessment and care of patients in a hospital are based on answers to the following questions: Who gets it? When do they get it? How much do they get? What route is used to administer it? What kind do they get? What are common complications of enteral and parenteral support? What nutritional aspects are pertinent to common diseases?

Clinical economics review: nutritional support

Nutritional support currently accounts for about 1% of the total health care costs in the USA. Interestingly, most of the prospective randomized controlled trials to date have not been able to demonstrate that this therapeutic intervention alters morbidity or mortality. In fact, parenteral nutritional support may predispose the recipients to developing systemic infections. There have been a few areas in which nutritional support may be of benefit. Enteral supplements given to underweight women who suffer hip fractures reduce the hospital stay and, presumably, overall cost. Preoperative parenteral nutritional support may produce a small absolute reduction in post-operative morbidity, but its cost becomes prohibitive. Preoperative enteral nutritional support, especially if carried out in the home, may be of benefit (using the most optimistic interpretation of a small number of trials); if so, it is an economically defensible intervention. Particular nutrients or diets may have specific effects on certain disease processes. Indirect comparisons have suggested that elemental diets can be used to treat flares of Crohn's disease (perhaps because putative food antigens are removed). However, corticosteroid therapy is more efficacious. Furthermore, it is less expensive to employ 6-mercaptopurine as the next modality in steroid failures. Branched-chain amino acid infusions may have some effect on hepatic encephalopathy, but again, lactulose is less expensive. Nutritional support is one area of medicine in which there has been far more enthusiasm than the data justify. Disease-associated malnutrition probably is a secondary phenomenon, not an important cause of morbidity. The widespread use of this modality cannot be justified in a cost-constrained health care system.

Nutrition support in clinical practice: review of published data and recommendations for future research directions. National Institutes of Health, American Society for Parenteral and Enteral Nutrition, and American Society for Clinical Nutrition

In the last 30 years, marked advances in enteral feeding techniques, venous access, and enteral and parenteral nutrient formulations have made it possible to provide nutrition support to almost all patients. Despite the abundant medical literature and widespread use of nutritional therapy, many areas of nutrition support remain controversial. Therefore, the leadership at the National Institutes of Health, The American Society for Parenteral and Enteral Nutrition, and The American Society for Clinical Nutrition convened an advisory committee to perform a critical review of the current medical literature evaluating the clinical use of nutrition support; the goal was to assess our current body of knowledge and to identify the issues that deserve further investigation. The panel was divided into five groups to evaluate the following areas: nutrition assessment, nutrition support in patients with gastrointestinal diseases, nutrition support in wasting diseases, nutrition support in critically ill patients, and perioperative nutrition support. The findings from each group are summarized in this report. This document is not meant to establish practice guidelines for nutrition support. The use of nutritional therapy requires a careful integration of data from pertinent clinical trials, clinical expertise in the illness or injury being treated, clinical expertise in nutritional therapy, and input from the patient and his/her family.

Glutamine-supplemented tube feedings versus total parenteral nutrition in children receiving intensive chemotherapy

Although enteral nutrition is generally advocated in the care of children with cancer, those patients receiving intensive chemotherapy alone or in combination with bone marrow transplantation often require total parenteral nutrition (TPN). Two patients are presented illustrating some differences between enteral and parenteral feedings in children receiving intensive chemotherapy. Nasogastric glutamine-supplemented tube feedings were well tolerated both in the hospital and at home. The cost of care for the enterally supported child was less than one third of the TPN-supported child. Although TPN appears to be beneficial in some patients with cancer, it is expensive and is associated with several significant disadvantages. Among these are an increased incidence of both gram-positive and gram-negative infections and an increased incidence of gastrointestinal symptoms. Enteral nutrition is less costly than TPN and maintains the structural and functional integrity of the intestinal mucosa. The addition of certain substrates such as glutamine, arginine and omega-3 fatty acids may improve the body's immune response as well. We hypothesize that early glutamine supplemented tube feedings in children receiving intensive chemotherapy alone or in combination with bone marrow transplantation will result in improved nutrition with fewer infections and lower cost than TPN-supplemented patients. In addition, a shorter hospital stay and improved quality of life are anticipated.

Cachexia and anorexia in malignancy

The cancer cachexia syndrome may be present in up to 80% of patients with cancer. Malnutrition resulting from cancer cachexia is a significant cause of morbidity and mortality. Anorexia, tissue wasting, and weight loss appear to be the result of metabolic abnormalities caused by host cytokine production in response to the tumor. The host cytokines include TNF-alpha, IL-1, IL-6, IFN-gamma, and D-factor. Nutritional support in the patient with cancer has been controversial, with the belief that tumor growth may be augmented; however, human studies fail to confirm that tumor growth occurs in excess of normal tissue growth. The efficacy of nutritional support in the cancer has not been adequately studied. Considerable interest exists in providing nutritional support pharmacologically to modify the response to malignancy.

Parenteral Nutrition Formulation: An Integral Part of the Endocrinologist’s Metabolic Support Consultation Service

Endocrinologists are uniquely suited to provide consultation in the new field of metabolic support. This specialty incorporates management of electrolyte and mineral disorders, diabetes mellitus, and malnutrition. Principles of formulation of parenteral nutrition are discussed, with an emphasis on distinguishing marasmus from kwashiorkor types of cachexia, disease-specific treatment, nutritional pharmacology, and relevant controversies.