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

OBJECTIVE: 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. DESIGN AND MEASUREMENTS: Patients underwent somatostatin receptor scintigraphy using ¹¹¹In-pentetreotide before slow-release octreotide was administered. The patients' symptoms, blood pressure, blood glucose concentrations, glycosylated haemoglobin concentrations, 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. RESULTS: 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. CONCLUSION: Our data suggest that slow-release octreotide is of limited value for the long-term treatment of patients with malignant or recurrent benign phaeochromocytomas.