Nutrition and tumor promotion: in vivo methods for measurement of cellular proliferation and protein metabolism

Dietary omega-3 polyunsaturated fatty acids plus vitamin E restore immunodeficiency and prolong survival for severely ill patients with generalized malignancy: a randomized control trial

BACKGROUND

The aim of the current prospective, randomized control study was to investigate the effect of dietary omega-3 polyunsaturated fatty acids plus vitamin E on the immune status and survival of well-nourished and malnourished patients with generalized malignancy.

METHODS

Sixty patients with generalized solid tumors were randomized to receive dietary supplementation with either fish oil (18 g of omega-3 polyunsaturated fatty acids, PUFA) or placebo daily until death. Each group included 15 well-nourished and 15 malnourished patients. The authors measured total T cells, T-helper cells, T-suppressor cells, natural killer cells, and the synthesis of interleukin-1, interleukin-6, and tumor necrosis factor by peripheral blood mononuclear cells before and on Day 40 of fish oil supplementation. Karnofsky performance status, nutritional state, and survival were also estimated.

RESULTS

The ratio of T-helper cells to T-suppressor cells was significantly lower in malnourished patients. Omega-3 PUFA had a considerable immunomodulating effect by increasing this ratio in the subgroup of malnourished patients. There were no significant differences in cytokine production among the various groups, except for a decrease in tumor necrosis factor production in malnourished cancer patients, which was restored by omega-3 fatty acids. The mean survival was significantly higher for the subgroup of well-nourished patients in both groups, whereas omega-3 fatty acids prolonged the survival of all the patients.

CONCLUSIONS

Malnutrition appears to be an important predictor of survival for patients with end stage malignant disease. Omega-3 polyunsaturated fatty acids had a significant immunomodulating effect and seemed to prolong the survival of malnourished patients with generalized malignancy.

Effect of methionine-deprived total parenteral nutrition on tumor protein turnover in rats

BACKGROUND

Previous studies have shown that a methionine-lacking diet inhibited tumor growth in rats. The aim of this study was to determine how methionine free total parenteral nutrition (MTPN) can result in the inhibition of tumor growth on tumor protein metabolism in rats.

METHODS

On day 0, AH109A rat ascites hepatoma cells were implanted subcutaneously into male Donryu rats (n = 68, body weight, 200-225 gm). On day 10, a catheter for total parenteral nutrition (TPN) was placed and either MTPN or standard TPN solution was given for 5 days. On day 15, 1-14C-leucine was infused continuously to measure tumor protein synthesis. Tumor proteolysis was calculated from tumor regional blood flow, using the 85Sr-microsphere injection method.

RESULTS

1) Tumor weight was reduced with MTPN. 2) MTPN did not affect tumor protein synthesis, probably because endogenous methionine production was increased with MTPN (87.3 +/- 13.5 mumole methionine/kg/hour vs. 218.6 +/- 29.5, P < 0.01); however, MTPN caused an increase of tumor proteolysis (2.68 +/- 0.53 mumole leucine/g/hour vs. 3.79 +/- 0.73, P < 0.05).

CONCLUSION

The enhanced tumor protein breakdown contributed to the inhibition of tumor growth that was found with the rats given the methionine free diet.

Treatment of anorexia with megestrol acetate

Anorexia and involuntary weight loss are prevalent problems in oncology and AIDS patients. Cytokines are suspected but not proven causes of cachexia. Megestrol acetate has been found to increase appetite, food intake, and weight in randomized, placebo-controlled trials in patients with advanced malignancies and in patients with AIDS. This hormone derivative probably has both central nervous system and peripheral metabolic effects. No significant effect on survival has been demonstrated in these trials. The optimal dose for appetite enhancement is unknown; we have chosen 320 mg/d as our initial dose. Megestrol acetate is usually well tolerated, and it may be helpful in the symptomatic and palliative therapy of patients with anorexia and weight loss.