Effects of artificial nutrition on the nutritional status of cancer patients

The paper critically analyzes available data on the nutritional and metabolic effects of total parenteral nutrition (TPN) and enteral nutrition (EN) in cachectic cancer patients. Only papers dealing with adult cancer patients and providing data regarding type of tumor, duration of the nutritional support, and administration rate of calories and amino acids, validated by statistical analysis of the results, are included. The main conclusions are the following: (1) No nutritional variable worsened in cancer patients receiving TPN or EN, in conditions in which progressive deterioration of the nutritional status is the rule. (2) The nutritional variables improved by TPN and EN were body weight, fat mass, and some indicators of lean body mass (nitrogen balance and whole body potassium). Thyroxin-binding prealbumin and retinol-binding protein increased only with TPN, whereas some immunologic indexes (complement factors and lymphocytes) improved only with EN. (3) The daily regimens which improved lean body mass and visceral proteins ranged from 35 to 55 kcal/kg and from 1.2 to 2.0 g of amino acids/kg for TPN; for EN it was 35 kcal/kg and 1.3 g of amino acids/kg. However, the enteral regimen capable of improving some immune responses included at least 42 kcal/kg and 2.3 g of amino acids/kg. (4) Only three randomized studies were performed to compare TPN and EN, and conflicting results were obtained. Only TPN showed some significant advantages with regard to weight gain, nitrogen balance, maintenance of serum albumin levels and some mineral balances. However, the advantage of TPN was not clear enough to recommend its indiscriminate use. The choice between TPN and EN should always consider the functionality of the GI tract, the need for hospitalization to start a TPN regimen, and the higher cost of intravenous feeding. (5) When comparing TPN to a standard oral diet, the following variables improved with the nutritional support: body weight, nitrogen balance, 3-methylhistidine, urinary excretion, and serum levels of transferrin, cholinesterase, thyroxin-binding prealbumin, and retinol-binding protein. (6) When comparing TPN with glucose vs TPN with glucose-lipids, no major difference was found with regard to most nutritional variables. In conclusion, nutritional support alone probably has a small role in managing a limited number of advanced cancer patients dying primarily because of malnutrition or mainly suffering from nutritional deterioration. It can also have a "permissive" role in those patients potentially candidate to an oncologic treatment which cannot be delivered because of a poor nutritional status.(ABSTRACT TRUNCATED AT 400 WORDS)