National Cancer Institute
Last Modified: November 30, 2011
Nutrition plays major (but not always fully understood) roles in many aspects of cancer development and treatment. 1 Malnutrition is a common problem in cancer patients that has been recognized as an important component of adverse outcomes, including increased morbidity and mortality and decreased quality of life. Weight loss has been identified as an indicator of poor prognosis in cancer patients. 2 It has been shown that at the time of diagnosis, 80% of patients with upper gastrointestinal cancer and 60% of patients with lung cancer have already experienced a significant weight loss, 3 generally defined as at least a 10% loss of body weight in 6 months' time. 4 Good nutrition practices can help cancer patients maintain weight and the body's nutrition stores, offering relief from nutrition impact symptoms and improving quality of life. 5 Poor nutrition practices, which can lead to undernutrition, can contribute to the incidence and severity of treatment side effects and increase the risk of infection, thereby reducing chances for survival. 6 Nutrition impact symptoms are those symptoms that impede oral intake. They include, but are not limited to, anorexia, nausea, vomiting, diarrhea, constipation, stomatitis, mucositis, dysphagia, alterations in taste and smell, pain, depression, and anxiety. 7 Early recognition and detection of risk for malnutrition through nutrition screening followed by comprehensive assessments is increasingly recognized as imperative in the development of standards of quality of care in oncology practices. 2 Undesirable weight gain may be an effect of chemotherapy treatment for early-stage cancers, possibly resulting from decreases in resting metabolism. 8 Consequently, the eating practices of individuals diagnosed with cancer should be assessed throughout the continuum of care to reflect the changing goals of nutritional therapy.
Nutritional status is often jeopardized by the natural progression of neoplastic disease. (Refer to the Tumor-Induced Effects on Nutritional Status section.) Alterations in nutritional status begin at diagnosis, when psychosocial issues may also adversely affect dietary intake, and proceed through treatment and recovery. Protein-calorie malnutrition (PCM) is the most common secondary diagnosis in individuals diagnosed with cancer, stemming from the inadequate intake of carbohydrate, protein, and fat to meet metabolic requirements and/or the reduced absorption of macronutrients. PCM in cancer results from multiple factors most often associated with anorexia, cachexia, and the early satiety sensation frequently experienced by individuals with cancer. These factors range from altered tastes to a physical inability to ingest or digest food, leading to reduced nutrient intake. Cancer-induced abnormalities in the metabolism of the major nutrients also increase the incidence of PCM. Such abnormalities may include glucose intolerance and insulin resistance, increased lipolysis, and increased whole-body protein turnover. If left untreated, PCM can lead to progressive wasting, weakness, and debilitation as protein synthesis is reduced and lean body mass is lost, possibly leading to death. 9
Anorexia, the loss of appetite or desire to eat, is typically present in 15% to 25% of all cancer patients at diagnosis and may also occur as a side effect of treatments. Anorexia is an almost universal side effect in individuals with widely metastatic disease 10 11 because of physiologic alterations in metabolism during carcinogenesis. (Refer to the Tumor-induced Effects on Nutritional Status section.) Anorexia can be exacerbated by chemotherapy and radiation therapy side effects such as taste and smell changes, nausea, and vomiting. Surgical procedures, including esophagectomy and gastrectomy, may produce early satiety, a premature feeling of fullness. 4 Depression, loss of personal interests or hope, and anxious thoughts may be enough to bring about anorexia and result in PCM. 3 Evidence-based recommendations have been published describing various approaches to the problems of cancer-related fatigue, anorexia, depression, and dyspnea. 12 Other systemic or local effects of cancer or its treatment that may affect nutritional status include hypermetabolism, sepsis, malabsorption, and obstructions. 9
Anorexia can hasten the course of cachexia, 3 a progressive wasting syndrome evidenced by weakness and a marked and progressive loss of body weight, fat, and muscle. Cachexia is estimated to be the immediate cause of death in 20% to 40% of cancer patients; it can develop in individuals who appear to be eating adequate calories and protein but have primary cachexia whereby tumor-related factors prevent maintenance of fat and muscle. Particularly at risk are patients with diseases of the gastrointestinal tract.
The etiology of cancer cachexia is not entirely understood. Cachexia can manifest in individuals with metastatic cancer as well as in individuals with localized disease. Several theories suggest that cachexia is caused by a complex mix of variables, including tumor-produced factors and metabolic abnormalities. 11 The basal metabolic rate in cachectic individuals is not adaptive, that is, it may be increased, decreased, or normal. 13 Some individuals do respond to nutrition therapy, but most will not see a complete reversal of the syndrome, even with aggressive therapy. 6 Thus, the most prudent and advantageous approach to cachexia is the prevention of its initiation through nutrition monitoring and nutrition intervention. 14
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In this summary, unless otherwise stated, evidence and practice issues as they relate to adults are discussed. The evidence and application to practice related to children may differ significantly from information related to adults. When specific information about the care of children is available, it is summarized under its own heading.
Nutritional status can be compromised in direct response to tumor-induced alterations in metabolism. Also known as cachexia, this condition is one of advanced protein-calorie malnutrition and is characterized by involuntary weight loss, muscle wasting, and decreased quality of life. 1 2 Tumor-induced weight loss occurs frequently in patients with solid tumors of the lung, pancreas, and upper gastrointestinal tract and less often in patients with breast cancer or lower gastrointestinal cancer. Although anorexia may also be present, the energy deficit alone does not explain the pathogenesis of cachexia. Several factors have been proposed. 3 Mediators including cytokines, neuropeptides, neurotransmitters, and tumor-derived factors are postulated to contribute to this syndrome. 4 Products of host tissues, such as tumor necrosis factor-, interleukin-1, interleukin-6, interferon-, and leukemia inhibitor factor, as well as tumor products that have a direct catabolic effect on host tissues, such as lipid-mobilizing factor and proteolysis-inducing factor (not established as definite in humans), have all been identified as mediators of this complex syndrome. 3 Altered metabolism of fats, proteins, and carbohydrates is evident in cancer patients with cachexia. Tumors may induce impaired glucose uptake and glucose oxidation, leading to an increased glycolysis. 5 Weight loss can occur from a decrease in energy intake, an increase in energy expenditure, or a combination of the two. Although anorexia is a common symptom of cancer patients, studies have shown that increased caloric intake either by the oral route or by supplementation with total parenteral nutrition has failed to counteract the wasting process. This supports the theory that the aberrant metabolic rate is the direct response by the tumor and the immune system to disrupt the pathways that regulate the homeostatic loop of body-weight regulation. 4
Current studies suggest that the basal metabolic rate serves as a possible prognostic indicator of survival. As cancer progresses, the basal metabolic rate declines and cachexia occurs, reducing long-term survival. 6 Although alterations in overall basal metabolic rates have not been observed by some, 7 increased basal metabolic rates have been reported in pediatric, 8 breast, 9 lung, 8 malnourished, 10 and other 11 cancer patient populations; however, the discrepancy may be related to the stage of cancer progression. 12 Nutritional support therapies aimed at preserving lean muscle mass and subcutaneous adipose stores despite this altered metabolic rate may ultimately improve patients' quality of life and impact overall survival.
Although an individual's nutritional status may be compromised initially by the diagnosis of cancer, thorough nutritional screening procedures and the timely implementation of nutritional therapies may markedly improve the patient's outcome. Symptoms and side effects may sometimes be managed by a combination of dietary and pharmacologic interventions.
Several approaches to the treatment of cancer cachexia have been reported, and a variety of agents have been studied for their effects on appetite and weight. The decision to use pharmacological treatment to improve a patient's appetite should be based on the patient's desires, current medical condition, and life expectancy. Table 1 lists several medications that have been proposed to treat the symptoms of cancer cachexia. 13 However, the management of cachexia remains a complex challenge, and integrated multimodal treatment targeting the different factors involved has been proposed. In a phase III study, patients were randomly assigned to receive megestrol acetate, eicosapentaenoic acid, L-carnitine, thalidomide, or megestrol acetate plus L-carnitine and thalidomide. Interim analysis of 125 patients suggested the most effective treatment would be a combination regimen. The optimal combination is the goal of ongoing research. 14
|Drug Category||Common Drugs Used||Comments|
|Progestational agents||megestrol acetate||Multiple investigations report appetite stimulant activity and weight gain with use. Body composition of weight gain indicates increased body fat stores instead of lean body tissue. Increased risk of thromboembolism with doses >800 mg/day is an apparent trend. Studies suggest improved effectiveness in patients with better digestive function; therefore, targeted nutritional strategies such as digestive enzymes or elemental diets may be useful.|
|Glucocorticoids||dexamethasone||Mechanism of appetite stimulation is unknown but likely related to anti-inflammatory and euphoric actions. Studies report positive but short-lived effects on clinical outcomes such as appetite and quality of life, with minimal or no effect on weight gain. Risk of adverse effects such as muscle wasting and immunosuppression limit use for long-term use for appetite stimulation.|
|Cannabinoids||dronabinol||Inconsistent evidence of clinical effectiveness in cancer patients. Studies of dronabinol alone or with megestrol acetate have not shown superior benefit in promoting weight gain and appetite.|
|Antihistamines||cyproheptadine||Not studied well in cancer patients. A randomized placebo-controlled trial in patients with advanced cancer reported no difference in weight changes and progressive weight loss in both groups. Sedation is a frequent adverse effect that may limit usefulness in cancer patients.|
|Antidepressants/ antipsychotics||mirtazapine||Clinical data supporting routine use in cancer patients are lacking. Further studies are needed.|
|Anti-inflammatory agents||thalidomide||All have been shown to decrease TNF-alpha. Mixed results in clinical trials regarding weight gain and appetite stimulation. One published randomized placebo-controlled trial evaluated the safety and efficacy of thalidomide, 200 mg daily, in patients with advanced pancreatic cancer and weight loss of at least 10% of premorbid weight. Thalidomide group showed a significant difference in weight loss compared with the placebo group, indicating the drug's ability to safely decrease weight loss and loss of lean body mass in the patients studied. Preliminary clinical studies and laboratory studies of the polyunsaturated fatty acid EPA have suggested a benefit to cancer patients; however, subsequent large comparative studies failed to reproduce this benefit.|
|omega 3 fatty acids (EPA)|
|Metabolic inhibitors||hydrazine sulfate||Not approved by the U.S. FDA for marketing in the United States.|
|Anabolic agents||oxandrolone||Used in an attempt to stimulate muscle anabolism. Limited published reports of successful appetite stimulation in cancer patients.|
|EPA = eicosapentaenoic acid; TNF-alpha = tumor necrosis factor-alpha; U.S. FDA = United States Food and Drug Administration.|
Weight loss associated with cancer and its treatment may be secondary to a host of symptoms and side effects. Early intervention using appropriate nutrition and pharmacologic symptom-management strategies can keep weight loss at bay. The drug categories typically used to manage these symptoms and side effects include the following: 25
The nutritional status of patients diagnosed with cancer entering the treatment process varies. Not everyone begins therapy with anorexia, weight loss, and other symptoms of nutritional problems. For patients who have such symptoms, however, anticancer therapies can complicate the treatment and expected recovery. Many individuals also present with preexisting comorbid diseases and illnesses that further complicate their treatment. Surgery, chemotherapy, and radiation can have a direct (or mechanical) and/or an indirect (or metabolic) negative effect on nutritional status. The success of the anticancer therapy will be influenced by a patient's ability to tolerate therapy, which will, in turn, be affected by nutritional status preceding treatment. The treating clinician should assess baseline nutritional status (see the Nutrition Screening and Assessment section) and be aware of the possible implications of the various therapies. Patients receiving aggressive cancer therapies typically need aggressive nutrition management.
Surgery is often the primary treatment modality for cancer. Approximately 60% of individuals diagnosed with cancer will have some type of cancer-related surgery. 1 Malnourished surgical patients are at increased risk for postoperative morbidity and mortality. Steps should be taken to attempt to correct nutritional macronutrient and micronutrient deficiencies before surgery if time permits. 2 This involves identification and assessment of the problem, with the possible use of oral liquid nutritional supplements, enteral or parenteral nutritional support, and/or use of pharmacologic therapies to stimulate the appetite (see the Tumor-Induced Effects on Nutritional Status section). 2
Depending on the procedure, surgery can cause mechanical or physiologic barriers to adequate nutrition, such as a short gut that results in malabsorption after bowel resection. 2 In addition to these mechanical barriers, surgery frequently imposes an immediate metabolic response that increases the energy needs and changes the nutrient requirements necessary for wound healing and recovery at a time when baseline needs and requirements are often not being met.
The following sections highlight various surgical issues for specific cancers. Nutritional complications are usually most notable and severe with cancerous growths and anticancer therapy involving the alimentary canal.
Alcohol abuse is a major risk factor for cancer in the head and neck region and can itself lead to malnutrition. 3 Cancer occurring in this region coupled with curative or palliative surgery can alter a patient's ability to speak, chew, salivate, swallow, smell, taste, and/or see. 2 Treatment for head and neck cancer can have a profound negative effect on nutritional status.
Nutrition assessment is advised at the initial visit. Clinicians should anticipate additional complicating factors such as the side effects of combined modality therapy (chemotherapy and radiation therapy), 4 as well as the increased nutritional requirements for withstanding these therapies. Because head and neck cancer patients are often malnourished at diagnosis and will undergo therapies that may directly affect their ability to eat, many of these individuals have enteral feeding tubes placed prophylactically before undergoing surgery. 2
Surgery may take a tremendous toll on the body, but it has reduced mortality and morbidity from gastrointestinal cancers. 2 Anticancer therapy for aerodigestive cancers (e.g., esophageal, gastric, pancreatic, liver, gallbladder, bile duct, and small and large intestine) can result in gastric paresis, alterations in digestion, malabsorption of nutrients, hyperglycemia, elevated lipid levels, hepatic encephalopathy, fluid and electrolyte imbalance, anastomotic and chyle leaks, dumping syndrome, and vitamin and mineral deficiencies. 2 The use of enteral nutritional support is common in the treatment of gastrointestinal cancers. The feeding tube may be placed in the stomach (gastrostomy) or down into the jejunum (jejunostomy). 2 5
Many individuals experience fatigue, pain, and loss of appetite and are unable to consume their regular diet as the result of surgery. 2 Prompt nutritional therapy can help relieve or reduce these problems. Avoiding carbonated or known gas-producing foods will help, as will altering the fiber content in the diet to encourage bowel regularity. A well-balanced diet that contains the recommended amounts of essential nutrients and calories will help promote good wound healing. Finally, proper nutrition and adequate rest may help prevent or treat fatigue.
In 2000, more than 90 different chemotherapy agents were approved for use. These agents are divided into several functional categories. Chemotherapy agents can be used in combination or as single agents, depending on the disease type and health condition of the individual. 6
Unlike surgery and radiation therapy, cancer chemotherapy is a systemic treatment (not a localized treatment) that affects the whole body (not just a specific part). 7 Consequently, there are potentially more side effects with chemotherapy than with surgery and radiation therapy. The most commonly experienced nutrition-related side effects are anorexia, taste changes, early satiety, nausea, vomiting, mucositis/esophagitis, diarrhea, and constipation (see the Nutritional Suggestions for Symptom Management section). Because side effects of chemotherapy, as well as the cancer itself, can greatly affect nutritional status, healthcare providers need to anticipate possible problems and educate the patient about them 7 in an effort to prevent malnutrition and weight loss (see the Nutrition Screening and Assessment section). Malnutrition and weight loss can affect a patient's ability to regain health and acceptable blood counts between chemotherapy cycles; this can directly affect the patient's ability to stay on treatment schedules, which is important in achieving a successful outcome.
Nutritional support or high-calorie/high-protein liquid supplements may be used in an effort to maintain adequate calorie and nutrient intake. Special formulas are available for people with secondary medical conditions such as hyperglycemia or compromised renal function.
Nutritional support during radiation therapy is vital. The effect of radiation therapy on healthy tissue in the treatment field can produce changes in normal physiologic function that may ultimately diminish a patient's nutritional status by interfering with ingestion, digestion, or absorption of nutrients. Medications such as pilocarpine (Salagen) may be useful in treating the xerostomia (dry mouth) that accompanies radiation therapy. This medicine may reduce the need for artificial saliva agents or other oral comfort agents such as hard candy or sugarless gum.
The side effects of radiation therapy depend on the area irradiated, total dose, fractionation, duration, and volume irradiated. Most side effects are acute, begin around the second or third week of treatment, and diminish 2 or 3 weeks after radiation therapy is completed. Some side effects can be chronic and continue or occur after treatment has been completed. 8
Individuals receiving radiation therapy to any part of the gastrointestinal tract are more susceptible to nutrition-related side effects. 9 Patients most at risk for developing nutrition-related side effects are those whose cancers involve the aerodigestive tract, including the head and neck, lungs, esophagus, cervix, uterus, colon, rectum, and pancreas. Patients who are receiving radiation therapy to the head and neck region may present to radiation therapy with preexisting malnutrition secondary to an inability to ingest foods because of the disease itself or because of surgery to treat the disease. Many of these patients have a history of high alcohol intake, which also places them at a higher nutritional risk. These individuals are generally at the greatest risk for developing significant nutrition problems and severe weight loss. 10 In a placebo-controlled, double-blind randomized study of 57 patients receiving radiation therapy for head/neck and lung cancer, megestrol acetate (MA) was administered at a dose of 800 mg per day. Patients who received MA demonstrated significant advantages in weight maintenance and some aspects of quality of life. 11
Nutrition intervention is based on symptom management. Patients who maintain good nutrition are more likely to tolerate the side effects of treatment. Adequate calories and protein can help maintain patient strength and prevent body tissues from further catabolism. Individuals who do not consume adequate calories and protein use stored nutrients as an energy source, which leads to protein wasting and further weight loss.
Some of the more common nutrition-related side effects caused by irradiation to the head and neck include taste alterations or aversions, odynophagia (pain produced by swallowing), xerostomia, thick saliva, mucositis, dysphagia, and stricture of the upper esophagus. 4 Thoracic irradiation may be associated with esophagitis, dysphagia, or esophageal reflux. Diarrhea, nausea, vomiting, enteritis, and malabsorption of nutrients are possible side effects of pelvic or abdominal radiation. 12 (See the Nutritional Suggestions for Symptom Management section.) A prospective, randomized study of patients with colorectal cancer receiving radiation therapy demonstrated that concurrent individualized dietary counseling can improve patients' nutritional intake, status, and quality of life. These improvements, in turn, may reduce radiation-induced morbidity. 13 Patients receiving high-dose radiation or bone marrow transplant should consult with a dietician.
Suggestions for appropriate dietary modifications based on nutrition-related symptoms are widely available for patient and healthcare professional use. For a full listing of dietary suggestions see the Tumor-Induced Effects on Nutritional Status section. A list of appropriate references is also included below.
Many patients who are undergoing radiation therapy will benefit from nutritional supplements between meals. 14 Aggressive nutritional support is indicated when oral intake alone fails to maintain an individual's weight. Tube feedings are used more frequently than parenteral nutrition, primarily to preserve gastrointestinal function. Tube feedings are usually well tolerated, pose less risk to the patient than parenteral feedings, and are more cost effective. Numerous studies demonstrate the benefit of enteral feedings initiated at the onset of treatment, specifically treatment to head and neck regions, before significant weight loss has occurred. 15 16 17
Many nutrition-related side effects result from radiation therapy. Quality of life and nutritional intake can be improved by managing these side effects through appropriate medical nutritional therapy and dietary modifications.
Monoclonal antibodies, which are used to block cancer-cell receptors for growth-stimulating factors, may cause a cascade of symptoms; however, the symptoms most likely to impact nutritional status are fever, nausea, vomiting, and diarrhea. 1 Interferon (a nonspecific immunotherapy) has had the noted nutrition-related side effects of anorexia, nausea, vomiting, and fatigue. 1 Interleukin-2, approved by the U.S. Food and Drug Administration for the single-agent treatment of metastatic renal cell cancer, can also cause symptoms such as fatigue, nausea, vomiting, and diarrhea. 1 18 Response to interleukin-2 treatment varies; some patients gain weight, and some require nutritional support. 18 However, most patients taking interleukin gain weight. Finally, granulocyte-macrophage colony-stimulating factor, a very common therapy used to increase the production of white blood cells, may also cause fever, nausea, vomiting, and diarrhea. 1
If ignored, these symptoms can cause gradual or drastic weight loss (depending on the severity of the symptoms), which may lead to malnutrition. Malnutrition can complicate the expected healing and recovery process (see the Nutritional Suggestions for Symptom Management section).
Hemopoietic and stem cell transplant patients have special nutritional requirements. 19 Before their transplant, patients receive high-dose chemotherapy and may also be treated with total-body irradiation (TBI). 20 These treatments, in addition to medications used during transplantation, frequently result in nutritional side effects, which may affect patients' ability to consume an adequate diet. The goal of nutritional support should be the maintenance of nutritional status and protein stores. In addition, transplant patients are at very high risk for neutropenia, an abnormally small number of neutrophils in the blood, that makes them susceptible to multiple infections. 21 22
To reduce the risk of infections related to stem cell transplantation, most healthcare setting guidelines recommend only cooked and processed foods and restrict raw vegetables and fresh fruits that could cause a food-related infection. Specific dietary restrictions and their duration depend on the type of transplant and the cancer site. In addition to specific dietary restrictions, food safety guidelines should be reviewed and stressed with all transplant patients.
The chemotherapy regimen and complications associated with the transplant may result in numerous problems that adversely affect nutritional intake and status. 23 During the transplant process, patients may experience nutrition-related side effects such as taste changes, oral dryness, thick saliva, mouth and throat sores, nausea and vomiting, diarrhea, constipation, lack of appetite/weight loss, and weight gain. Often during the first few weeks posttransplant, patients are fed intravenously to ensure that they receive sufficient calories, protein, vitamins, minerals, and fluids. 24
Many patients experience mouth and throat sores 2 to 4 weeks after transplantation. Mucositis is the general term that refers to the erythema, swelling, and ulceration of the intraoral soft-tissue structures and the oral and esophageal mucosa in response to the cytotoxic effect of radiation therapy and high-dose chemotherapy. Mouth and throat sores can make eating and swallowing difficult. TBI may also cause dryness of the mouth, temporarily alter the taste of food, and/or cause thick saliva to form in the mouth and throat. Nausea and vomiting are common problems experienced by transplant patients. Nausea and vomiting may be caused by TBI, chemotherapy, and some medications. TBI, chemotherapy, infection, depression, and fatigue can cause a decrease in appetite and weight loss. Lack of appetite may continue to be a problem long after discharge from the hospital. Patients may also experience gastrointestinal problems such as diarrhea and constipation that could be caused by TBI, chemotherapy, gastrointestinal graft-versus-host disease, infection, and some medications. 25 26
Nutrition in cancer care embodies prevention of disease, treatment, cure, or supportive palliation. Caution should be exercised when considering alternative or unproven nutritional therapies during all phases of cancer treatment and supportive palliation, as these diets may prove harmful. Patient nutritional status plays an integral role in determining not only risk of developing cancer but also risk of therapy-related toxicity and medical outcomes. Whether the goal of cancer treatment is cure or palliation, early detection of nutritional problems and prompt intervention are essential.
The original principles of nutrition care for people diagnosed with cancer were developed in 1979 1 and are still very relevant today. Proactive nutritional care can prevent or reduce the complications typically associated with the treatment of cancer. 1
Many nutritional problems stem from local effects of the tumor. Tumors in the gastrointestinal tract, for example, can cause obstruction, nausea, vomiting, impaired digestion, and/or malabsorption. In addition to the effects of the tumor, marked alterations in normal metabolism of carbohydrates, protein, and/or fats can occur. 2
The nutritional prognostic indicators most recognized as being predictive of poor outcome include weight loss, wasting, and malnutrition. In addition, significant weight loss at the time of diagnosis has been associated with decreased survival and reduced response to surgery, radiation therapy, and/or chemotherapy. 3
Malnutrition and accompanying weight loss can be part of an individual's presentation or can be caused or aggravated by treatments for the disease. Identification of nutrition problems and treatment of nutrition-related sym