Entire section revised: 15 April 2003
Purpose of Nutritional Care During Cancer Treatment
- To restore or conserve nutritional status, body composition and functional status prior to, during and after cancer treatment
- To minimize food related discomfort associated with cancer and/or its treatment
- To improve strength, well-being and quality of life
Indications for Use
The following nutrition guidelines are intended for individuals who are at risk for or display evidence of nutritional deficiencies secondary to cancer and/or its treatment. Nutrition care is an important factor in cancer care, encompassing primary prevention, diagnosis and treatment, recurrence risk reductions, and palliation.
Description of the Diet
Dietary modifications should be based on patient tolerance, tumour site, treatment and associated side effects, stage of disease, and any pre-existing diseases/ disorders requiring nutrition therapy. The provision of appropriate food consistency depends on the severity of eating problems. Complex nutritional problems may require a combination of nutritional interventions or alternative routes of feeding.
Discussion
Cancer Cachexia Syndrome
This constitutes the most significant clinical problem associated with cancer. It manifests itself primarily through weight loss, anorexia, early satiety and chronic nausea (1, 2). Its pathogenesis and mechanisms are complex and less well understood than those of pure chronic starvation. Cancer cachexia can have a profound effect on quality of life by decreasing physical function, impairing performance status, impairing activities of daily living, and contributing to depression and decreased social interactions (3). Proactive nutrition assessment and early intervention in addressing symptoms of cancer cachexia are the cornerstones of successful nutrition management of the individual living with cancer (1).
Nutrition Assessment
Tumour and Treatment Side Effects
When assessing nutritional status, the following factors should be considered in addition to standard nutrition assessment parameters:
- Primary tumour site affected and presence of metastases
- Type and frequency of treatment(s) and potential side effects, such as nausea, vomiting, lack of appetite, dysphagia or diarrhea
- The effect of malignancy on the ingestion, digestion and absorption of nutrients
- Pre-existing medical conditions (e.g. diabetes mellitus)
Weight Status
Weight status is the best indicator of nutritional status in the individual living with cancer. Weight loss of > 5% of body weight in one month or > 10% in six months signals nutritional risk (4). Weight loss is a major prognostic indicator of survival, response to therapy and quality of life (1). Weight loss may occur in all stages of the disease, and the extent of weight loss varies with the individual, tumour site and stage, and type of cancer treatment. It is important to note that weight loss alone is not a good measurement of nutritional status in the presence of edema, ascites, or dehydration. Skinfold measurements and height-weight standards may also be of limited use in these cases (5).
Current Food Intake
A 24 hour recall and a food frequency assessment are helpful in determining adequacy of intake. It is important to assess the diet with respect to specific symptoms experienced. For example, if diarrhea is a concern, particular attention should be given to intake of fibre, fluid, caffeine, fat, lactose, alcohol and spices (5).
Energy and Protein Requirements
There may be an increase in resting energy expenditure (REE) in patients with some types of cancer; this appears more prevalent in those patients who have lost weight (3). Individuals living with cancer can be hypo- or hyper-metabolic; therefore mathematical formulas for predicting energy and protein requirements are of limited use. Instead, the combination of serial body weights, measurements of daily energy and protein intakes, and assessment of muscle wasting are more reliable indicators of energy and protein adequacy (5). In certain instances such as planning enteral or parenteral feedings, baseline estimates of nutritional requirements are needed.
Laboratory Analyses
The interpretation of laboratory results in nutritional assessment must be done carefully as cancer and/or its treatment frequently result in abnormal values independent of nutritional status. A diet and weight history are usually more meaningful than laboratory data in assessing the nutritional status of individuals living with cancer (5).
Provision of Nutritional Care
Macronutrients
Protein energy malnutrition is the single most common secondary diagnosis in cancer patients (6). Thus, increasing energy and protein intake is the most important intervention for improving nutritional status. Unlike chronic starvation, where there is preferential mobilization of fat over muscle protein, in cancer cachexia there is equal mobilization of fat and skeletal muscle (2). There is also enhanced whole-body lipolysis, leading to an increase in plasma free fatty acids and glycerol (2). In terms of carbohydrate metabolism, there is an increase in the recycling of glucose through the lactate pathway and an increase in gluconeogenesis. The high levels of lactic acid produced significantly contribute to anorexia (6).
When an adequate intake cannot be achieved orally, enteral or parenteral support may be necessary to prevent or respond to malnutrition. When food intake is inadequate, yet the GI tract is functional, provision of enteral feedings may be useful (3). A retrospective review of a nonrandomized study in patients with locally advanced head and neck cancer treated by radiation with or without chemotherapy suggests that prophylactic gastrostomy tubes can reduce weight loss and the rate of hospitalization (7). However, studies on total parenteral nutrition (TPN) showed an increase in infectious and mechanical complications in patients receiving chemotherapy who were given TPN (8). Overall, this warrants the careful use of TPN for patients who are:
- unable to maintain adequate nutrition due to tumor obstruction (9);
- experiencing treatment side effects; or
- preoperative for tumour resection (3).
Micronutrients
It is not known whether cancer and/or its treatment increases micronutrient needs (10). Factors affecting the ability to meet micronutrient needs include disease location and process, treatment modality and medications. Tumours located in the digestive tract have the potential of causing obstruction resulting in poor intake and therefore micronutrient deficiency. Deficiency of B vitamins can arise from prolonged general malnutrition (6). Normal metabolism of micronutrients may also be altered by disease process. Hypercalcemia resulting from disease cannot be regulated through diet therefore restriction may not be required (11). Resection of the lower gastrointestinal tract may result in malabsorption and micronutrient deficiencies.
Radiation induced side effects can cause generalized poor intake, which may result in micronutrient deficiencies. Greater losses of electrolytes may occur with radiation-related nausea, vomiting and diarrhea. Chemotherapy can have a direct effect on micronutrient levels. For instance, carboplatin can decrease serum electrolytes, specifically magnesium and potassium (12). Asparaginase can cause azotemia accompanied by an increase in calcium and phosphorous excretion due to increased protein degradation (12). Side effects of chemotherapeutic agents such as nausea, vomiting and diarrhea, can lead to electrolyte imbalances. Other commonly used drugs can alter micronutrient levels (e.g. use of antibiotics can lead to electrolyte imbalance secondary to diarrhea) (5).
A daily multivitamin and mineral supplement may be recommended for individuals whose micronutrient intake is limited for a prolonged period. Due to potential interactions between specific chemotherapy medications and vitamins, patients receiving chemotherapy should consult their physician before taking supplements. Megadoses of vitamins and minerals are not advisable due to their potential toxicity or actual impairment of immune function (i.e. zinc) (13).
Complementary and Alternative Therapies
Complementary and alternative medicines (CAM), many of which are nutrition related, are widely sought by cancer patients and their families (6). Alternative therapies are therapies used instead of conventional therapy, to treat cancer. Complementary therapies are those used in conjunction with conventional therapy for symptom management and enhancement of quality of life (14). Health professionals are often asked to provide an opinion on a variety of herbal preparations and the use of megadoses of vitamins and minerals in the prevention and treatment of cancer. When evaluating a therapy, the following questions should be considered (6):
- Has the therapy been proven to be more effective than providing no intervention?
- Is the therapy as safe as doing nothing?
- Does the potential for benefit exceed the potential for harm to the patient and family?
- Have proponents of the therapy demonstrated its efficacy and safety?
- What is the cost of the therapy, and what are its financial implications for the patient?
As part of the nutrition assessment, it is important to determine the patient's current nutrition intake, the type of nutrition regimes/ herbal preparations/ supplements used, the extent to which these replace nutritional intake, and the risk of interactions or potential toxicities with conventional treatment.
As well, the potential harmful effects of herbal preparations and megadoses of vitamins/ minerals must be discussed with the patient. These harmful effects include:
- Risk of contamination, adulteration, misidentification, fake products, illegal ingredients
- Lack of regulation or quality control
- Possible interactions that interfere with radiotherapy and chemotherapy regimes
- Adverse effects (allergic reactions, nausea, vomiting, diarrhea, sedation); "natural" does not mean harmless
More research is necessary to provide scientific support for the use of herbal preparations and megadoses of vitamins and/or minerals in the treatment of cancer. Until more is known, dietitians and other health professionals should be able to discuss with the patient the pros and cons of a particular therapy in an objective, nonjudgmental, and supportive manner, with genuine concern for and interest in the patient's well-being (15).
Use of Concurrent Therapeutic Diets
Therapeutic diets for co-existing diseases, such as diabetes or coronary artery disease, often need to be liberalized during cancer treatment in order to achieve adequate energy and protein intakes. Dietary restrictions are seldom appropriate for the individual with terminal illness.
Use of Nutritional Supplements
Commercial nutritional supplements may be useful for increasing energy and/or protein intake in individuals unable to meet their nutritional requirements through conventional foods (16). Individuals should be informed regarding suitable homemade alternatives in order to avoid common problems associated with extensive use of commercial products such as inappropriate dilution, and taste fatigue. The dietitian may want to explore the use of commercial supplements if the following exist:
- Impairment in the ability to consume and/or prepare conventional nutrient dense foods and fluids
- Dysgeusia
- Lactose intolerance
Practical Considerations
Practical considerations relating to patient concerns about daily living must be addressed when counseling the individual living with cancer. These considerations include:
- Ability to shop for food and prepare meals
- Financial situation and potential need for financial assistance
- Existing eating habits and ability, as well as motivation to make dietary changes
- Family dynamics and the use of food as a comfort or control measure
Primary Cancer Prevention
Diet has an important role to play in cancer prevention. There is strong and consistent evidence that a plant based diet protects against different tumours. In 1997 an international expert panel published a comprehensive set of 15 dietary recommendations designed to reduce cancer risk globally (17). These guidelines encompass food choices, body weight, physical activity, alcohol consumption, food processing, cooking methods and use of dietary supplements. The guidelines promote a low fat, minimally processed, predominantly plant-based diet, and discourage intake of alcohol, red meat and refined sugar to a greater extent than have earlier cancer prevention guidelines.
There is growing interest in the cancer protective role of phytochemicals – substances in plant foods with biological effects in the human body. For example, organosulfur compounds found in cruciferous vegetables increase the activity of enzymes which detoxify carcinogens in the liver. Other phytochemicals of note include allyl sulfides, isoflavones, lignans, monoterpenes, phenolic acids, saponins, polyphenols and carotenoids (18). Of these, the isoflavones and lignans are of special interest because of their estrogen-like biological activity. The two main classes of phytoestrogens, isolflavones and lignans, are primarily found in soybeans and soyfoods, flax seeds, grains, fruits and vegetables. There is much research interest in the role of these phytoestrogens in the prevention and treatment of breast and prostate cancers. Until more definitive guidelines are available, individuals are advised to consume whole foods containing phytoestrogens , rather than concentrated isoflavone supplements (19).
Guidelines for the Prevention of Cancer Recurrence
At present, it is unclear whether the dietary recommendations for cancer prevention can also be used for reducing the risk of cancer recurrence. This might be because the factors that influence the initial stages of cancer may differ from those implicated in cancer recurrence. Research studies are currently being conducted to answer this question. At present, scientists believe that dietary guidelines for cancer prevention are not likely to be detrimental to an individual who has had cancer, and may in fact lower the risk of cancer recurrence (20).
Palliative Care
In the palliative care setting, the pleasurable aspects of eating should be emphasized without concern for quantity or nutrient content. Enteral or parenteral feedings should be considered only if such therapy is mutually agreed upon by the individual and caregiver to improve quality of life.
Additional Resources
BC Cancer Agency Nutrition Services
- Centre for the Southern Interior
(250) 712.3963
Toll free in B.C. 1.888.563.7773
- Fraser Valley Centre
(604) 930.4000
Toll free in B.C. 1.800.523.2885
- Vancouver Centre
(604) 877.6000 ext. 2013
Toll free in B.C. 1.800.663.3333 ext. 2013
- Vancouver Island Centre
(250) 519.5525
Toll free in B.C. 1.800.670.3322
Nutritional Guidelines for Symptom Management
Requests for these can be made to BC Cancer Agency Vancouver Centre Nutrition Services.
Dietitians of Canada (DC)
Oncology Nutrition Network Dietetic Practice Group
For more information contact Dietitians of Canada
http://www.dietitians.ca/
480 University Avenue, Suite 604, Toronto, Ontario M5G 1V2
Phone: 416.596.0857
Fax: 416.596.0603
e-mail: centralinfo@dietitians.ca
National Cancer Institute of Canada
http://www.ncic.cancer.ca/
Suite 200, 10 Alcorn Avenue, Toronto, Ontario, M4V 3B1
Phone: 416.961.7223
Fax: 416.961.4189
e-mail: ncic@cancer.ca
Canadian Cancer Society
http://www.cancer.ca
phone: 1-800-227-2345
Websites
References
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- Chandra RK. Excessive intake of zinc impairs immune responses. J AM Med Assoc.1984; 252:1443-1446
- Cassileth BR. Evaluating complementary and alternative therapies for cancer patients. CA-A Cancer Journ for Clin 1999; 49(6);362-375
- Holland JC. Why patients seek unproven cancer remedies: A psychological perspective. CA-A Cancer Journ for Clin (1982); 32,20
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- World Cancer Research Fund and the American Institute for Cancer Research.(1997). Food, Nutrition and the Prevention of Cancer: a global perspective. Washington, DC
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- Collins, K. After Cancer. Nutrition Notes. American Institute for Cancer Research. Sept 1998
©2000, American Dietetic Association. Used with permission.