title: The octreotide suppression test and [111In-DTPA-D-Phe1]-octreotide scintigraphy in neuroendocrine tumours correlate with responsiveness to somatostatin analogue treatment.
abstract: OBJECTIVE
  The somatostatin analogue octreotide (Sandostatin, Novartis, Basie) significantly improves the syndromes suffered by most patients with neuroendocrine tumours (NETs). The use of [111In-DTPA-D-Phe1]-octreotide scintigraphy ([111In]-pentetreotide) to predict the response to octreotide treatment has been described. Short-term hormone inhibition by a single injection of octreotide has also been reported. This study aimed to compare the effects of the suppression test with the response to long-term somatostatin analogue treatment, and to seek a correlation between the short-term suppression test, [11In]-pentetreotide observations and long-term somatostatin analogue treatment.
  
  
  METHODS
  Short octreotide suppression test and octreotide scintigraphy. Blood samples were collected before (0900, 0930 h), at (1000 h), and after (1030, 1100, 1200, 1300 h) the injection of 50 micrograms octreotide subcutaneously. Plasma hormones relevant to the syndrome were analysed by radioimmunoassay. The short suppression effects, the [111In]-pentetreotide observations and the response to long-term treatment with somatostatin analogue were evaluated and compared.
  
  
  METHODS
  Twenty-six patients with metastatic NETs were evaluated, including 14 carcinoid tumours, 10 pancreatic endocrine tumours and 2 medullary carcinomas of thyroid (MCTs). Twelve patients had received octreotide treatment before the study, another 4 patients were treated subsequently with somatostatin analogue.
  
  
  RESULTS
  During the short suppression test, hormones relevant to the syndromes were suppressed in 24 patients (those with carcinoids and pancreatic endocrine tumours). There was no suppression in the 2 patients with MCT. [111In]-pentetreotide observations closely correlated with the short suppression response to octreotide. Fourteen patients were treated with somatostatin analogue, and responded clinically; they had a positive short inhibition test and positive tumour uptake. Two patients with MCT did not respond to the treatment and had a negative suppression test and a negative [111In]-pentetreotide.
  
  
  CONCLUSIONS
  Our results suggest that a consistent relationship exists between the short suppression test and the response to somatostatin analogue treatment in the majority of the patients with neuroendocrine tumours. The octreotide suppression test and octreotide scintigraphy together will be helpful in selecting appropriate patients for clinical treatment with somatostatin analogues.
authors.affiliation: Wellcome Research Laboratories, Division of Metabolism and Endocrinology, School of Clinical Medicine, Queen's University of Belfast, UK.
authors.forename: W
authors.initials: W
authors.lastname: Shi
authors.forename: K D
authors.initials: KD
authors.lastname: Buchanan
authors.forename: C F
authors.initials: CF
authors.lastname: Johnston
authors.forename: C
authors.initials: C
authors.lastname: Larkin
authors.forename: Y L
authors.initials: YL
authors.lastname: Ong
authors.forename: R
authors.initials: R
authors.lastname: Ferguson
authors.forename: J
authors.initials: J
authors.lastname: Laird
mesh_terms: D000328:Adult; D000368:Aged; D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use*; D015415:Biomarkers / Q000097:blood; D003864:Depression, Chemical; D005069:Evaluation Studies as Topic; D005260:Female; D006801:Humans; D007205:Indium Radioisotopes; D008297:Male; D008875:Middle Aged; D018358:Neuroendocrine Tumors / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000188:drug therapy*; D015282:Octreotide / Q000627:therapeutic use*; D011379:Prognosis; D011877:Radionuclide Imaging; D013004:Somatostatin / Q000031:analogs & derivatives*; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D018931:Antineoplastic Agents, Hormonal; D015415:Biomarkers; D007205:Indium Radioisotopes; D013004:Somatostatin; C081788:pentetreotide; D015282:Octreotide