Endocrine Abstracts

Neuroendocrine tumours (NETs) are usually taken to include gastro-enterohepatic tumors including islet cell tumours and carcinoids; recent data suggest an overall incidence of around 30/million/year, but since such tumours usually present late curative surgery is rarely an option and chemotherapy of limited benefit. Radionuclide scintigraphy with somatostatin (SMS) analogues such as 111In-octreotide demonstrate the presence of SMS receptors in some 80%-90% of NETS; we have used such imaging to demonstrate a 15% prevalence of ocular metastases in patients with carcinoid tumours. Such staging, particularly with co-imaging CT scanning, can often change management by the unexpected demonstration of distant metastases. Patients with NETs usually show good hormonal and symptomatic control with SMS analogues such as Sandostatin LAR or Lanreotide Autogel by monthly injection, and in some cases these may have a tumoristatic effect. Radiolabelled lanreotide and octreotide have also been reported to be of therapeutic benefit The imaging agent ¹¹¹In-octreotide is mainly a gamma-emitter, but the local formation of Auger electrons allows it have to some limited therapeutic benefit. ⁹⁰Y-lanreotide has been shown to be efficacious in causing tumour stabilisation with some tumour regression in a large multicentre European trial (MAURITIUS), but uptake with ¹¹¹In-octreotide does not necessarily imply uptake of the lanreotide analogue. More recently, a large scale international trial of 90Y-octreotide (Octreother, SMT 487, Novartis) of some 279 patients has been completed, and data on these patients will be reported after trial closure late in 2004. Preliminary data form our own group of patients show that this treatment is well tolerated, and improves biochemical control in some patients, but survival has been poor. Other analogues, such as ¹⁷⁷Lu-octreotate, are also under investigation, and may complement ⁹⁰Y-octreotide depending on lesion size. Optimisation of treatment protocols with these agents, either alone or in combination, may offer a novel therapeutic approach to these difficult tumours.