The studies were grouped according to the treatment given for the cancer.
Surgery: 22 trials (greater than 1,784 patients) evaluated parenteral nutrition and 7 (400 patients) trials evaluated enteral nutrition.
Chemotherapy: 18 trials (752 patients) evaluated parenteral nutrition and 7 trials (340 patients) evaluated enteral nutrition.
Radiation therapy: 4 trials (166 patients) evaluated parenteral nutrition and 7 trials (260 patients) evaluated enteral nutrition.
Bone marrow transplantation: 2 trials (198 patients) evaluated parenteral nutrition; in one of these trials, the comparator group was given enteral nutrition.
Surgery.
Data from the trials that provided at least 7 days of pre-operative parenteral nutrition suggested that the rate of major peri-operative complications could be decreased by approximately 5%. However, the cost of providing pre-operative parenteral nutrition for 7 to 10 days to 20 patients, to eliminate one post-operative complication, may not be economical. The majority of the trials suggested that there was no significant difference between the treatment groups in terms of the length of hospital stay. Enteral nutrition by tube feeding was associated with gastrointestinal intolerance (nausea, vomiting, abdominal pain, distention and diarrhoea) in up to 50% of the patients. Catheter dysfunction occurred in 20 to 25% of the patients fed by needle-catheter jejunostomy. Peri-operative mortality and the duration of hospital stay were similar in both the treatment and control groups. The rate of peri-operative complications that were not associated with tube feeding was 15% less in patients given enteral feedings than in the control groups.
Chemotherapy.
Parenteral nutrition had no obvious effect on survival. The tumour response rates tended to be worse in patients receiving parenteral nutrition, and there was no apparent beneficial effect on haematologic or gastrointestinal toxicity. In the majority of the trials (8 out of 9), the infection rates were higher in patients receiving parenteral nutrition; this trend was statistically significant in 3 trials. Studies examining enteral nutrition were difficult to evaluate because of heterogeneous nutrition therapy and methodological flaws. Enteral nutrition had no obvious therapeutic benefit with respect to survival, tumour response, or chemotherapy toxicity.
Radiation therapy.
There was no difference in survival between patients receiving parenteral nutrition and those in control groups. One study suggested that parenteral nutrition resulted in a decrease in gastrointestinal side-effects, whereas 2 other studies indicated that it was associated with an increase in gastrointestinal or haematologic side-effects. The infection rates were higher with parenteral nutrition in the one study that reported this outcome. Enteral nutrition did not improve survival and its effect on haematologic or gastrointestinal side-effects was unclear.
Bone marrow transplantation.
The effect of parenteral nutrition on survival was unclear, but it appears that there is unlikely to be a difference between patient groups receiving nutrition support and control groups. In the trial that compared both parenteral nutrition and enteral nutrition, the infection rates were higher in the former. The cost of maintaining enteral nutrition was less than half the cost of parenteral nutrition.