Nutrition plays major (but not always fully understood) roles in many aspects of cancer development and treatment. 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. 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, generally defined as at least a 10% loss of body weight in 6 months' time. 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. 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. 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. 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. Undesirable weight gain may be an effect of chemotherapy treatment for early-stage cancers, possibly resulting from decreases in resting metabolism. 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.
Purpose of This Summary
This PDQ cancer information summary for health professionals provides comprehensive, peer-reviewed, evidence-based information about the risks of continued smoking in cancer patients and about quitting patterns and cessation intervention in these patients. It is intended as a resource to inform and assist clinicians who care for cancer patients. It does not provide formal guidelines or recommendations for making health care decisions.
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