technetium-tc-99m-depreotide and Neuroendocrine-Tumors

Somatostatin receptor imaging (SRI) with [(111)In-DTPA(0)]octreotide has proven its role in the diagnosis and staging of gastroenteropancreatic neuroendocrine tumors (GEPNETs). Newer radiolabeled somatostatin analogs which can be used in positron emission tomography (PET) imaging, and which have a higher affinity for the somatostatin receptor, especially receptor subtype-2, have been developed. It would be desirable, however, if one radiolabeled analog became the new standard for PET imaging, because the current application of a multitude of analogs implies a fragmented knowledge on the interpretation of the images that are obtained in clinical practice. In our view, the most likely candidates for such a universal PET tracer for SRI are [(68)Ga-DOTA(0),Tyr(3)]octreotate or [(68)Ga-DOTA(0),Tyr(3)]octreotide. Treatment with radiolabeled somatostatin analogs is a promising new tool in the management of patients with inoperable or metastasized neuroendocrine tumors. Symptomatic improvement may occur with all (111)In-, (90)Y-, or (177)Lu-labeled somatostatin analogs that have been used for peptide receptor radionuclide therapy (PRRT). The results that were obtained with [(90)Y-DOTA(0),Tyr(3)]octreotide and [(177)Lu-DOTA(0),Tyr(3)]octreotate are very encouraging in terms of tumor regression. Also, if kidney protective agents are used, the side effects of this therapy are few and mild, and the median duration of the therapy response for these radiopharmaceuticals is 30 and 40 months respectively. The patients' self-assessed quality of life increases significantly after treatment with [(177)Lu-DOTA(0),Tyr(3)]octreotate. Lastly, compared to historical controls, there is a benefit in overall survival of several years from the time of diagnosis in patients treated with [(177)Lu-DOTA(0),Tyr(3)]octreotate. These data compare favorably with the limited number of alternative treatment approaches. If more widespread use of PRRT can be guaranteed, such therapy may well become the therapy of first choice in patients with metastasized or inoperable GEPNETs.

Topics: Animals; Antineoplastic Agents; Clinical Trials as Topic; Combined Modality Therapy; Digestive System Neoplasms; Gallium Radioisotopes; Humans; Indium Radioisotopes; Neuroendocrine Tumors; Octreotide; Organometallic Compounds; Organotechnetium Compounds; Peptides, Cyclic; Positron-Emission Tomography; Quality of Life; Radiopharmaceuticals; Receptors, Somatostatin; Somatostatin; Treatment Outcome; Yttrium Radioisotopes

The somatostatin analogue octreotide was the first radiopeptide to be used for the scintigraphic diagnosis of tumors. Somatostatin receptor scintigraphy (SRS) has proven its value, especially in the detection of gut neuroendocrine tumors. In some tumor types, it is considered the diagnostic gold standard. In carcinoid tumors of the lung, SRS is of major importance in diagnostic workup. Furthermore, the combination of computed tomography scanning and SRS is a reliable and cost-effective approach for the evaluation of single pulmonary nodules. Despite these favorable properties, SRS fails in the detection of metastases of lung cancer. The problem of false-positive results in SRS resulting from inflammatory disease might be overcome by the use of new radiopeptides such as cholecystokinin-B receptor-binding gastrin analogues. This article focuses on the current status of peptide-receptor scintigraphy in the diagnosis of lung tumors and on future developments in this field.

Topics: Cost-Benefit Analysis; Diagnosis, Differential; Gastrointestinal Agents; Humans; Lung Neoplasms; Neoplasm Metastasis; Neuroendocrine Tumors; Octreotide; Organotechnetium Compounds; Peptides, Cyclic; Prognosis; Radionuclide Imaging; Somatostatin; Tomography, X-Ray Computed