The aim of this study was to assess the feasibility of somatostatin receptor scintigraphy (SRS) for the detection of the site of unknown primary neuroendocrine neoplasms in patients in whom clinical examination and conventional radiological imaging had failed to do so. From 1996 to 2000, 36 patients were referred with gastro-entero-pancreatic (GEP) neuroendocrine tumours. In these patients, no clinical, radiological or endoscopic diagnostic modalities had been able to identify the primary tumour. Twenty-nine patients had liver metastases. Of the others, one had skin and one had lymph node metastases, three had diffuse metastatic involvement and two had carcinoid syndrome. SRS was carried out with both whole-body and single-photon emission tomography (SPET) acquisition, 24 and 48 h after the intravenous administration of 111In-pentetreotide. SRS findings were suggestive of the possible site of the primary lesion in 14 patients (39%). Six patients underwent surgery on the basis of the SRS findings and, therefore, the final, i.e. pathological, diagnosis was reached. In two patients, the final diagnosis was obtained within 6 months of SRS by means of a follow-up computed tomography (CT) scan. In the remaining six patients, the final diagnosis was reached after at least 2 years of follow-up by means of clinical, radiological and/or nuclear medicine findings. In all eight patients, the primary site identified during follow-up was consistent with the SRS findings. It can be concluded that SRS modified management in the six patients who had surgery. However, the most important finding was that SRS prompted surgical management in 17% of cases.
aDivision of Nuclear Medicine, Istituto Nazionale Tumori, Milan, Italy
bInstitute of Radiological Sciences, University of Milan and unit of Molecular Imaging Division of Radiation therapy, European Institute of Oncology, Italy
cDivision of Radiology, Istituto Nazionale Tumori, Milan, Italy
Sponsorship: This study was supported in part by an AIRC grant (Associazione Italiana Ricerca Cancro, Milano, Italy) and CNR funds (Council for National Research, Rome, Italy)
Correspondence to Dr Emilio Bombardieri, Division of Nuclear Medicine, Istituto Nazionale Tumori, via G. Venezian, 1, 20133 Milano, Italy
Tel: +39 02 2390 2220; fax: +39 02 2367 874;
Received 20 July 2003 Accepted 14 August 2003