Nutrition therapy for the cancer patient.

Malnutrition commonly occurs in cancer and adversely affects the quality of life and survival of patients. It is caused by a variety of factors, including decreased food intake, adverse effects from anticancer treatment, and wasteful metabolic processes. Over the past 2 decades, there have been major advances in methods and techniques of feeding patients with cancer and other disease. Special diets can be helpful in the treatment of a variety of conditions, some of which are outlined in Table 1. Enteral feeding is developing rapidly because endoscopic techniques have made it simpler to place feeding tubes, and a variety of enteral feeding solutions are commercially available. Enteral feeding is an effective way to deliver nutrients when patients are unable to ingest food because of neurologic disorders or structural abnormalities in the upper gastrointestinal tract, including the oropharynx, esophagus, and stomach. The role of enteral feeding as an adjuvant to anticancer therapy has not been fully evaluated. Parenteral nutrition is an effective method of delivering nutrients into the blood stream. It has proved to be life-saving for patients with chronic severe gastrointestinal insufficiency (such as short bowel or radiation enteritis), whose cancer is cured or nonprogressive. Numerous studies have assessed the role of TPN as an adjuvant therapy. To date, a clear benefit from its routine use has been demonstrated only in very limited, specific situations. As an adjuvant to chemotherapy, TPN does not seem to be useful, unless there are prolonged periods of gastrointestinal toxicity (as in the case with bone marrow transplantation) that severely limit oral intake and absorption. Malnourished surgical patients undergoing specific major operations for cancer may benefit from perioperative TPN. TPN as an adjunct therapy in the treatment of the cancer patient has to be individually evaluated and appropriately applied in situations in which it has proven beneficial in randomized studies.