Somatostatin-receptor imaging in the localization of endocrine tumors

Article Abstract:

In recent years, great advances have been made in the study of numerous cell surface receptors. It has been found that some tumors bear receptors for the peptide hormone somatostatin, and this observation can be used to clinical advantage. Patients with carcinoids, particular tumors arising in the gastrointestinal tract, and patients with tumors of the endocrine pancreas can be relieved of symptoms through the administration of octreotide, a molecule similar in structure to somatostatin. Octreotide apparently interacts with the somatostatin receptors and blocks the excessive secretion of hormones. This same substance may also be used in another role. Radioactively-labelled octreotide will bind to the somatostatin receptors on primary tumors and on metastatic tumors, as well. A camera sensitive to gamma rays can then be used to provide an image of the octreotide binding, which localizes the tumor. This use of octreotide was investigated in 13 patients with metastatic carcinoid disease and in nine patients with pancreatic endocrine tumors. Octreotide labelled with iodine-123 was administered; this is a radioactive isotope of iodine with a short half-life of 13.3 hours. In 12 of 13 carcinoid patients and in seven of nine patients with pancreatic tumors, successful visualization of the tumors was accomplished. Furthermore, in all patients in whom visualization was accomplished, metastatic tumors were observed which were unknown at the time of imaging. In the two pancreatic tumor patients for whom imaging was not successful, histopathological investigation revealed that no somatostatin receptors were present. For the single carcinoid patient for whom imaging was unsuccessful, histopathological examination was not performed, but this same patient failed to respond to octreotide therapy, suggesting a lack of somatostatin receptors. The results indicate that the radioactive labelling of receptors on tumor cells and their subsequent visualization can identify tumor masses as small as one centimeter, and reveal the presence of metastatic tumors which are not easily visualized by other procedures. (Consumer Summary produced by Reliance Medical Information, Inc.)

Research, Diagnosis, Hormone receptors, Tumors, Diagnostic imaging, Medical imaging equipment, Pancreatic tumors, Radioisotopes in medical diagnosis, Radioisotopic diagnosis

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Carcinoid tumors

Article Abstract:

Carcinoid tumors are most often found in the lungs, gastrointestinal tract, and heart. They have many characteristics of neuroendocrine tissue, and secrete hormones and substances such as serotonin. Many are benign, but some can metastasize, or spread to other organs. Even patients with metastatic disease can be free of symptoms for years. Derivatives of somatostatin can be used to treat metastatic disease because over 80% of carcinoid tumors have somatostatin receptors. Interferon alpha has also been used but with limited success. Surgery can be used for liver metastases.

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Treatment of type II gastric carcinoid tumors with somatostatin analogues

Article Abstract:

Long-term treatment with somatostatin analogues was found to be effective on tumor regression in three patients with type II gastric carcinoid tumor as revealed by gastroscopic examination. In one patient, the drug completely eliminated more than 30 tumors after one year of treatment.

Italy, Evaluation, Drug therapy, Illustration, Chemotherapy, Stomach cancer, Somatostatin, Gastrin, Gastroscopy

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