To characterize the effects of enteral versus parenteral nutritional support on protein metabolism in the cancer patient, patients with localized, squamous cell carcinoma of the distal esophagus were randomized to receive nutritional support as follows: (1) if there was a loss of less than 20% of the preillness body weight, patients were randomized to continue eating ad libitum (group I) versus receiving total parenteral nutrition (TPN) (group II); (2) if there was a loss greater than 20% of the preillness body weight and/or the patient was unable to swallow, patients were randomized to jejunostomy feedings (group III) versus TPN (group IV). Patients were initially studied in the postabsorptive state and again 2 weeks after beginning, and while receiving, enteral or parenteral feedings. Stable isotopic tracer methods utilizing constant infusion of [15N]glycine were used to determine whole-body protein turnover (flux), synthesis, and catabolism. Skeletal muscle catabolism was determined by measuring the urinary excretion of 3-methylhistidine and lean tissue mass was evaluated by determining total-body potassium by 40K whole-body scanning. Positive nitrogen balance was obtained in groups II and IV associated with significant weight gain in both; the changes in weight were not significant in groups I and III. Whole-body protein flux increased in all groups, but significantly only in group II. Synthesis increased in groups II and IV and decreased in I and III, but not significantly. Catabolism tended to decrease in all groups but group 1. Urinary 3-methylhistidine excretion decreased in groups II and IV signifying decreased skeletal muscle catabolism, but increased in groups I and III. Total body potassium tended to increase in groups II and IV. In this group of patients with localized squamous cell carcinoma of the esophagus, both TPN and jejunal feedings tended to stabilize nutritional status and whole-body protein economics. TPN appeared to be slightly more efficacious, although the differences between enteral and parenteral nutritional support in this study were slight.
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