Nutrition plays major (but not always fully understood) roles in many aspects of cancer development and treatment. Of cancer-related deaths, 20% to 40% may result from nutritional status rather than the disease itself.[1] In individuals diagnosed with cancer, factors that affect nutritional well-being are variable, and ongoing monitoring is essential to prevent or reverse complications resulting from a depleted state.[2] Good nutrition practices can help cancer patients maintain weight and the body's nutrition stores, offering relief from nausea or constipation and improving quality of life.[3] 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.[4] 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.[5] Malnourished individuals also run the risk of compromised immune function because of the depletion of lymphocytes and other cells as well as the depressed production of factors involved with immunity.[1]

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 [6,7] 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.[8] Depression, loss of personal interests or hope, and anxious thoughts may be enough to bring about anorexia and result in PCM.[2] Other systemic or local effects of cancer or its treatment that may affect nutritional status include hypermetabolism, sepsis, malabsorption, and obstructions.[5]

Anorexia can hasten the course of cachexia, a progressive wasting syndrome,[8] 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 are malabsorbing nutrients because of the disease. 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. Cachexia does not appear to be the result of tumor size, type, or extent. Several theories suggest cachexia is caused by a complex mix of variables, including tumor-produced factors and metabolic abnormalities.[7] The basal metabolic rate in cachectic individuals is not adaptive, that is, it may be increased, decreased, or normal.[9] Some individuals do respond to nutrition therapy, but most will not see a complete reversal of the syndrome, even with aggressive therapy.[4] Thus, the most prudent and advantageous approach to cachexia is the prevention of its initiation through nutrition monitoring and nutrition intervention.[1]

Reference citations in some PDQ Supportive Care information summaries may include links to external Web sites that are operated by individuals or organizations for the purpose of marketing or advocating the use of specific treatments or products. These reference citations are included for informational purposes only. Their inclusion should not be viewed as an endorsement of the content of the Web sites or of any treatment or product by the PDQ Supportive Care Editorial Board or the National Cancer Institute (NCI).

References

1. Zeman FJ: Nutrition and cancer. In: Zeman FJ: Clinical Nutrition and Dietetics. 2nd ed. New York, NY: Macmillan Pub . Co, 1991, pp 571-98. 
   
   
2. Ross BT: Cancer's impact on the nutrition status of patients. In: Bloch AS: Nutrition Management of the Cancer Patient. Rockville, Md: Aspen Publishers, 1990, pp 11-3. 
   
   
3. American Cancer Society.: Nutrition for the Person with Cancer: A Guide for Patients and Families. Atlanta, Ga: American Cancer Society, Inc., 2000. 
   
   
4. Vigano A, Watanabe S, Bruera E: Anorexia and cachexia in advanced cancer patients. Cancer Surv 21: 99-115, 1994.  [PUBMED Abstract]
   
   
5. Shils ME: Nutrition and diet in cancer management. In: Shils ME, Olson JA, Shike M, et al., eds.: Modern Nutrition in Health and Disease. 9th ed. Baltimore, Md: Williams & Wilkins, 1999, pp 1317-47. 
   
   
6. Langstein HN, Norton JA: Mechanisms of cancer cachexia. Hematol Oncol Clin North Am 5 (1): 103-23, 1991.  [PUBMED Abstract]
   
   
7. Tisdale MJ: Cancer cachexia. Anticancer Drugs 4 (2): 115-25, 1993.  [PUBMED Abstract]
   
   
8. Shils ME: Nutrition needs of cancer patients. In: Bloch AS: Nutrition Management of the Cancer Patient. Rockville, Md: Aspen Publishers, 1990, pp 3-10. 
   
   
9. Ottery FD: Cancer cachexia: prevention, early diagnosis, and management. Cancer Pract 2 (2): 123-31, 1994 Mar-Apr.  [PUBMED Abstract]
   
   

Back to Top

Next Section >