(dtpa-phe(1))-octreotide and Melanoma

The medical approach to patients with secreting or clinically non-functioning pituitary adenoma as made considerable progress thanks to the use of new somatostatin analogs. They were first used to treat acromegaly in the mid 1980s and numerous studies have shown a reduction in GH concentration in over 90% of acromegalic patients. Good results were obtained using slow-release analog treatment also in TSH-secreting adenomas, whereas the therapeutic efficacy of these peptides in clinically non-functioning adenomas is still controversial. Treatment with somatostatin analogs improves symptoms, normalises hormone secretion and in some cases may induce a reduction in the volume of pituitary adenomas. Scintigraphy with octreotide may help to select patients who respond to this form of treatment.

Topics: Acromegaly; Adenoma; Adolescent; Adrenal Gland Neoplasms; Adult; Aged; Antineoplastic Agents, Hormonal; Carcinoma; Humans; Indium Radioisotopes; Insulin-Like Growth Factor I; Kidney Neoplasms; Melanoma; Middle Aged; Octreotide; Pentetic Acid; Peptides, Cyclic; Pheochromocytoma; Pituitary Neoplasms; Predictive Value of Tests; Prolactinoma; Radionuclide Imaging; Radiopharmaceuticals; Sensitivity and Specificity; Somatostatin; Thymoma; Thymus Neoplasms; Thyroid Neoplasms; Thyrotropin; Treatment Outcome

Sixty-six patients with a clinical and neuroradiological diagnosis of CNS tumors were evaluated by 111In-octreotide scintigraphy. Planar images were acquired at 2-4 and 24 hours after the injection of 111-185 MBq of 111In-octreotide (Octreoscan, Byk-Gulden). In the positive scans the tumor/non-tumor ratio was evaluated using a standard ROI method, and an uptake index (U.I.) of the lesion was determined. In vitro binding assays were performed on frozen sections from surgical specimens from 17 patients. All 32 meningiomas demonstrated a positive 111In-octreotide scan with a high U.I. Only 13 of 21 gliomas showed a positive scan, but the U.I. was significantly lower (p < 0.001 by "t"-test); one lymphoma showed a faint tracer uptake. All the other histotypes evaluated yielded negative scans. In all cases the receptorial pattern shown by the immunohistochemical staining technique was concordant with the scintigraphic results. 111In-octreotide scintigraphy allowed a differential diagnosis of meningioma versus other CNS tumors in 6 patients (4 neurinomas, 1 brain metastasis of melanoma, 1 lymphoma). In conclusion, 111In-octreotide scintigraphy is a promising tool to evaluate the SS receptorial pattern of CNS tumors and to increase the diagnostic specificity of conventional imaging providing useful information in selected cases for the therapeutic strategy.

Topics: Brain Neoplasms; Central Nervous System Neoplasms; Diagnosis, Differential; Follow-Up Studies; Frozen Sections; Glioma; Humans; Immunohistochemistry; Indium Radioisotopes; Lymphoma; Melanoma; Meningioma; Neurilemmoma; Octreotide; Pentetic Acid; Radionuclide Imaging; Radiopharmaceuticals; Receptors, Somatostatin