Endocrine Abstracts

BACKGROUND: We have previously demonstrated that in weight losing gastrointestinal cancer patients appetite is poor despite low circulating leptin concentrations. One explanation for the apparent inability of these low circulating leptin concentrations to increase appetite might be a decrease in the leptin binding component resulting in high concentrations of 'free' biologically active leptin. The present study was designed to investigate this possibility, furthermore the effect of the appetite stimulant megesterol acetate on leptin and leptin binding.

PATIENTS AND METHODS: Age matched weight stable (9M:4F) and weight losing (9M:4F) cancer patients were studied. Weight losing patients (8M:2F) were also studied before and during 6 - 12 wks megesterol acetate treatment (480 mg/day). Serum leptin was measured by an 'in house' radioimmunoassay. Leptin binding was determined by Sephadex G-100 gel filtration. Appetite was measured using a visual analogue scale. Percentage fat mass was measured using bioelectrical impedance. The study was approved by the local ethical committee.

RESULTS: In weight stable and weight-losing cancer patients there was a positive relationship between leptin and appetite (r=0.458, p<0.01), percentage fat mass (r=0.574, p<0.01) and free leptin (r=0.561, p<0.01). Weight losing cancer patients had reduced BMI (p= 0.08), appetite (p<0.01), total leptin (p<0.01) and free leptin (p<0.01). On megesterol acetate treatment appetite improved (p=0.08) and leptin increased (p=0.032).

CONCLUSIONS: Abnormal leptin binding did not occur in the majority of cancer patients studied. Paradoxically, leptin was positively correlated with appetite in gastrointestinal cancer patients. In addition our results indicate that megesterol acetate increases both appetite and circulating leptin concentrations.