Cancer is a group name for more than 100 different types of malignancies characterized by the uncontrolled growth of cells. Individual cancers differ in where they develop, how quickly they grow, the type of treatment they respond to, and how much they affect nutritional status. Cancer is currently the second leading cause of death in the United States (S. Murphy, Kochanek, Xu, & Arias, 2015) but is expected to surpass heart disease as the leading cause of death in the next few years (
Siegel, Miller, & Jemal, 2015).
Nutrition in Cancer Prevention
Tobacco cessation is inarguably the leading behavioral strategy for reducing the risk of cancer. For nontobacco users, the most important modifiable determinants of cancer risk are body weight, dietary choices, and levels of physical activity (
Kushi et al., 2012). Cancer prevention guidelines to maintain healthy body weight, increase physical activity, consume a healthy eating pattern, and avoid excessive alcohol intake (
Table 22.1) are also associated with a lower risk of cardiovascular disease (CVD) and diabetes (
Ford et al., 2009). Adhering to guidelines to reduce the risk of cancer has been shown to reduce the risk of dying from cancer, CVD, and all causes combined (
McCullough et al., 2011). All people, including cancer survivors, are urged to adopt healthy lifestyle behaviors to reduce the risk of cancer and other chronic diseases.
The focus of nutrition guidelines has shifted away from single nutrients or food groups and toward eating patterns because of the complex mixtures and interactions between food components.
Reedy et al. (2014) found that people who adhered closest to any of the four healthy eating patterns studied, including the Mediterranean-style and DASH eating patterns, had a 12% to 28% decreased risk of all-cause, CVD, and cancer mortality. Results did not show that any single component of the eating patterns was largely responsible for the outcome but suggest whole grains, vegetables, fruit, and plant-based proteins are beneficial.
Trichopoulou, Lagiou, Kuper, and Tichopoulos (2000) estimate that up to 25% of colorectal cancer; 15% of breast cancer; and 10% of prostate, pancreas, and endometrial cancers could be prevented if populations of Western countries adopt a traditional Mediterranean-style eating pattern. Protective benefits of a Mediterranean-style eating pattern may be due to its emphasis on plant foods and olive oil and its relatively low intake of red meat, processed meat, and sweets (
Giacosa et al., 2013).
Currently, there is insufficient evidence to support the use of multivitamin and mineral supplements or single vitamins or minerals for cancer prevention (
Fortmann, Burda, Senger, Lin, & Whitlock, 2013). Antioxidants, such as beta-carotene, vitamin C, and vitamin E have been theorized to have a preventive role in cancer; however, studies have not confirmed benefit and have even demonstrated an increased risk from consuming these nutrients through supplements. For instance, studies have shown increases in lung cancer risk in smokers and former smokers taking beta-carotene supplements (
Gallicchio et al., 2008) and increases in prostate cancer risk in men taking vitamin E supplements (
Klein et al., 2011). In the Women’s Antioxidant Cardiovascular Study, total cancer incidence was not lowered in women taking supplements of vitamin C, vitamin E, or beta-carotene when compared to a placebo (
Lin et al., 2009). Other nutrients of interest include vitamin D and omega-3 fatty acids, both of which are currently being studied for their effect on cancer risk in a large scale randomized trial (
Manson et al., 2012).
The Impact of Cancer on Nutrition
Nutrition is affected in multiple ways by cancer and its treatment, some of which are listed in
Box 22.1. Malnutrition is a common problem in patients with cancer and is associated with increased morbidity and mortality and decreased quality of life (NCI, 2016). Depending on the site of the cancer, 15% to 69% of patients with upper GI cancer have already experienced significant weight loss, defined as a loss of at least 10% of body weight in 6 months at the time of diagnosis (
Silvers, Savva, Huggins, Truby, & Haines, 2014). Weight loss is an indicator of poor prognosis in people with cancer. Local tumor effects and metabolic changes contribute to the risk of malnutrition and weight loss.
Local Tumor Effects
Local tumor effects occur when the tumor impinges on surrounding tissue, impairing its ability to function. The effects vary with the site and size of the tumor and are most likely to affect nutrition when the GI tract is involved (
Table 22.2). GI obstruction can cause anorexia, dysphagia, early satiety, nausea, vomiting, pain, or diarrhea, leading to weight loss and malnutrition.
Metabolic Changes and Cachexia
Tumor-induced weight loss occurs frequently in patients with solid tumors of the lung, pancreas, and upper GI tract (
NCI, 2016). Tumor cells can produce proinflammatory and procachectic factors that stimulate inflammation and the breakdown of body protein and fat. The body responds with inflammatory and endocrine changes. The interplay between tumor and host leads to a systemic inflammatory response. The catabolic state is characterized by insulin resistance, decreased muscle protein synthesis, increased body protein turnover, and accelerated fat breakdown.
The cascade of metabolic changes resulting from the effects of the tumor, the body’s response, and the host-tumor interaction can lead to cancer cachexia, an advanced protein calorie malnutrition characterized by involuntary weight loss, muscle wasting, and decreased quality of life (
Donohoe, Ryan, & Reynolds, 2011). States of
cachexia in cancer are (
Thompson et al., 2016)
Cachexia a wasting syndrome associated with cancer characterized by progressive loss of body weight, fat, and lean body mass.
Precachexia, characterized by loss of appetite and altered glucose intolerance. Precachexia may precede substantial involuntary weight loss (e.g., up to 5% of weight). Factors that influence its variable progression include cancer type, cancer stage, systemic inflammation, inadequate food intake, and lack of response to anticancer therapy.
Cachexia, a multifactorial syndrome characterized by ongoing loss of skeletal muscle mass (with or without loss of fat mass) that leads to progressive functional impairment. Major features include negative protein and calorie balance. Any patient who has experienced unintentional weight loss is considered at risk for cachexia. Cachexia cannot be treated with nutrition therapy alone because although anorexia is frequently present, abnormal metabolism and inflammation are contributing factors.
Refractory cachexia, which may result from very advanced cancer or a rapidly progressive cancer that is unresponsive to anticancer therapy. This stage is actively catabolic and efforts to manage weight loss are no longer possible or appropriate. Life expectancy is less than 3 months.
Management of cachexia is a complex challenge. Early interventions to prevent weight loss in precachexia or cachexia are more likely to be effective than interventions that are delayed (
Thompson et al., 2016). Medications to control side effects of cancer and its treatment, such as nausea, diarrhea, constipation, dry mouth, and pain, may help prevent weight loss. Medications to stimulate appetite and promote weight gain may be used, depending on the patient’s wishes, medical condition, and life expectancy (
Table 22.3). Nutrition therapy aimed at preserving lean muscle mass and fat stores may improve quality of life and affect overall survival (NCI, 2016).
The Impact of Cancer Treatments
Cancer treatments include surgery, chemotherapy, radiation, immunotherapy, hemopoietic and stem cell transplantation, or a combination of therapies. Each treatment modality can contribute to progressive nutritional deterioration related to localized or systemic side effects that interfere with intake, increase nutrient losses, or alter metabolism. Comorbidities may complicate treatment and nutritional status. The success of treatment is influenced by the patient’s ability to tolerate therapy, which is affected by nutritional status. Patients who undergo aggressive cancer treatment typically need aggressive nutrition management (NCI, 2016).
Nutrition therapy, used as an adjuvant to effective cancer therapy, helps to sustain the client through adverse side effects and may reduce morbidity and mortality. Adequate calories and protein help prevent catabolism and loss of
lean body mass. Oral nutrition supplements are commonly used. Enteral nutrition initiated before treatment begins, especially in patients treated for head and neck cancers, and may help prevent significant weight loss. Conversely, inadequate nutrition can contribute to the incidence and severity of treatment side effects and increase the risk of infection, thereby reducing the chance for survival (
Vigano, Watanabe, & Bruera, 1994).
Lean Body Mass the weight of the body minus the weight of fat.
Surgery
Surgery is often the primary treatment for cancer. People who are malnourished prior to surgery are at higher risk of postoperative morbidity and mortality. If time allows, nutritional deficiencies are corrected before surgery and may require the use of oral nutrition supplements, enteral or parenteral nutrition, and/or use of medications to stimulate appetite.
Postsurgical nutritional requirements increase for protein, calories, vitamin C, B vitamins, and iron to replenish losses and promote healing. Physiologic or mechanical barriers to good nutrition can occur depending on the type of surgery, with the greatest likelihood of complications arising from GI surgeries.
Table 22.4 outlines potential side effects and complications incurred for various types of surgery.
Chemotherapy
Given alone or in combination, chemotherapy drugs damage the reproductive ability of both malignant and normal cells, especially rapidly dividing cells such as well-nourished cancer cells and normal cells of the GI tract, respiratory system, bone marrow, skin, and gonadal tissue. Cyclic administration of multiple drugs is given in maximum-tolerated doses.
The side effects of chemotherapy vary with the type of drug or combination of drugs used, dose, rate of excretion, duration of treatment, and individual tolerance. Chemotherapy side effects are systemic and, therefore, potentially more numerous than the localized effects seen with surgery or radiation. The most commonly experienced nutrition-related side effects are anorexia, taste alterations, early satiety, nausea, vomiting, mucositis/esophagitis, diarrhea, and constipation (NCI, 2016). Side effects increase the risk of malnutrition and weight loss, which may prolong recovery time between treatments. When subsequent chemotherapy treatments are delayed, successful treatment outcome is potentially threatened.
Radiation
Radiation causes cell death; particles of radioactive energy break chemical bonds, disrupting reproductive ability. Although radiation injures all rapidly dividing cells, it is most lethal for the poorly differentiated and rapidly proliferating cells of cancer tissue. Recovery from sublethal doses of radiation occurs in the interval between the first dose and subsequent doses. Normal tissue appears to recover more quickly from radiation damage than does cancerous tissue.
The type and intensity of radiation side effects depend on the type of radiation used, the site, the volume of tissue irradiated, the dose of radiation, the duration of therapy, and individual tolerance. Patients most at risk for nutrition-related side effects are those who have cancers of the head and neck, lungs, esophagus, cervix, uterus, colon, rectum, and pancreas (
Table 22.5). Side effects usually develop around the second or third week of treatment and then diminish 2 or 3 weeks after radiation therapy is completed. Some side effects may be chronic.
Immunotherapy
Immunotherapy seeks to enhance the body’s immune system to help control cancer. The most common side effects include fever, which increases protein and calorie requirements, and nausea, vomiting, diarrhea, anorexia, and fatigue. Actual side effects depend on the type of immunotherapy used. Left untreated, symptoms can cause gradual or drastic weight loss, which can lead to malnutrition and complicated or delayed recovery.
Hemopoietic and Peripheral Blood Stem Cell Transplantation
Hemopoietic and stem cell transplants are preceded by high-dose chemotherapy and possibly total-body irradiation to suppress immune function and destroy cancer cells. Numerous nutritional side effects may arise from these treatments and immunosuppressant medications, which are given before and after the procedure. Anorexia, taste alterations, nausea, vomiting, dry mouth, thick saliva, mucositis, stomatitis, and esophagitis may occur. Intestinal damage may cause severe diarrhea, malabsorption, and weight changes.
Parenteral nutrition may be needed for 1 to 2 months after bone marrow transplantation to ensure an adequate intake. When an oral diet resumes, a liquid diet restricted in lactose, fiber, and fat is given to minimize malabsorption and improve tolerance. Solid foods are gradually reintroduced.
Neutropenia leaves the patient susceptible to infection, so precautionary measures must be taken to prevent foodborne illness (
Box 22.2); however, a
neutropenic diet is generally not necessary, although facility protocols differ. A high-protein, high-calcium diet may be needed to counter the negative nitrogen and calcium balances caused by immunosuppressant medications.
Neutropenia abnormally low number of neutrophils in the blood, which increases the risk of infection.
Neutropenic Diet a diet intended to protect people with low neutrophil counts from bacteria and other organisms in some food and drinks. Eliminates fresh fruits, vegetables, raw nuts, yogurt, and other products with live active cultures.
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