Effects of slow-release octreotide on urinary metanephrine excretion and plasma chromogranin A and catecholamine levels in patients with malignant or recurrent phaeochromocytoma.

Abstract

Somatostatin receptors are present on human phaeochromocytomas. Catecholamine concentrations may decrease following short-term administration of somatostatin agonists to patients with phaeochromocytomas. We carried out a prospective study on 10 patients with malignant or recurrent phaeochromocytomas to examine the clinical and hormonal effects of three monthly intramuscular injections of 20 mg slow-release octreotide. Patients underwent somatostatin receptor scintigraphy using 111In-pentetreotide before slow-release octreotide was administered. The patients' symptoms, blood pressure, blood glucose concentrations, glycosylated haemoglobin concentra-tions, plasma insulin and noradrenaline concentrations, and the levels of two putative markers of tumour burden, urinary metanephrine excretion and plasma chromogranin A concentration, were recorded before the first injection and 28 days after the third injection. Slow-release octreotide did not significantly alter symptoms, blood pressure, blood glucose concentrations, plasma catecholamine and chromogranin A concentrations or metanephrine excretion. Median glycosylated haemoglobin concentrations increased from 5.3% to 6.0% (P = 0.03). Patients whose tumours took up 111In- pentetreotide did not differ from those whose tumours did not after slow-release octreotide treatment in terms of symptoms, blood pressure, blood glucose, plasma catecholamine and chromogranin A concentrations or metanephrine excretion. Our data suggest that slow-release octreotide is of limited value for the long-term treatment of patients with malignant or recurrent benign phaeochromocytomas.