SOMATOSTATIN AND SOMATOSTATIN ANALOGS IN MEDULLARY-THYROID CARCINOMA

Medullary thyroid carcinoma (MTC) is a neuroendocrine tumour character ized by the production and secretion of calcitonin. MTC tumours may ex press functional somatostatin receptors (hSSTR). A significant proport ion of hSSTR receptor-positive MTC tumours, including metastatic disea se, may be visualized in vivo through In-111-pentetreotide scintigraph y. Four patients with recurrent/metastatic disease, who had previously been assessed with In-111-anti-CEA monoclonal antibody fragment [F(ab ')(2)] imaging, were evaluated. In-111-pentetreotide scintigraphy loca lized all known disease sites. Furthermore, mediastinal disease was de tected in one patient with negative conventional and In-111-anti-CEA F (ab')(2) imaging studies. The detection of somatostatin within the tum our (2 patients), or negative octreotide challenges (2 patients), did not affect the outcome of In-111-pentetreotide scintigraphy. In conclu sion, In-111-pentetreotide scintigraphy appears at least as effective as In-111-anti-CEA F(ab')(2) imaging and should be considered in the d iagnostic evaluation of MTC, particularly in the setting of recurrent/ metastatic disease not detected by conventional means.