The prognostic value of somatostatin-receptors scintigraphy in neuroendocrine tumours.

The aim of this study is to assess the prognostic value of the 111-In-DTPA-D-Phe-1-Octreotide (Octreoscan) in the evaluation of Neuroendocrine Tumours. Thirty-seven patients were studied using Octreoscan by SPECT at 4 hours and at 24 hours from injection. The pathologic diagnosis was Neuroblastoma (9 cases), Small Cell Lung Cancer (5 cases), Not Small Cell Lung Cancer (1 case), Medullary Thyroid Carcinoma (5 cases) and Gastroenteric Pancreatic Tumour (17 cases). Ten of these patients, treated with cold Octreotide, were re-evaluated by SPECT at 26 hours (Displacement Test). The Statistical Analysis is performed using Linear Discriminant Function (LDF) validated using the so-called “Jack-knife” cross-validation procedure by Minitab® Computer Statistical program. The ratio between the activity content of disease localisation and of background (T/NT) was utilised for quantification. A T/NT increment between 4 hours and 24 hours was considered a sign of specific uptake. Octreotide scintigraphy did not yield false-positive results. The results of the displacement test are equivalent to the T/NT4hvs .24h ratios. The data showed a high accuracy (92%) of the T/NT4hvs .24h ratios in comparison with the prognosis. The sensitivity for Neuroendocrine Tumours was not influenced by the localisation and amounts uniformly to 88%. Our results suggest that radiolabeled Octreotide can be used to characterise SST receptors expressed by Neuroendocrine tumours and it can represent a prognostic index in the clinical management.