Somatostatin receptor imaging and therapy of pancreatic endocrine tumors.

Somatostatin receptors (SS-Rs) have been found on a variety of neuroendocrine tumors like carcinoids, paragangliomas, as well as on brain and breast tumors. SS-Rs are also present on most pancreatic endocrine tumors, while previous in vitro studies indicate the absence of these receptors on pancreatic duct cancers. Somatostatin receptor scintigraphy with a radionuclide labeled somatostatin analogue, [111In-DTPA0]-octreotide, is a sensitive and specific technique to visualize in vivo the presence of SS-Rs on various tumors. The purpose of this article is to review the somatostatin receptor imaging of pancreatic endocrine tumors and to illustrate the impact of SS-R expression for therapeutic strategies.

[Mucinous breast carcinomas with neuroendocrine differentiation]. / Mutsinozni kartsinomi na g'rdata s nevroendokrinna diferentsiatsiia.

Mucinous breast carcinomas, denominated also gelatinous, mucoid and colloid (collomas), represent a heterogeneous group of neoplasms. More than half of them exhibit signs of neuroendocrine differentiation. Eighteen mucus producing carcinomas of the breast are subjected to morphological study. On the ground of demonstrating argyrophilia by the methods of Grimelius and Churukian--Shenk, and presence of secreting granules during electron microscopic study, they are assigned under the heading apudomas, i.e. tumors of the diffuse endocrine system, or the so-called APUD-system. The important practical implications of demonstrating neuroendocrine cells with a special reference to the biological patterns of this particular type of tumors are discussed.

Regulatory peptides and other neuroendocrine markers in medullary carcinoma of the thyroid.

Medullary thyroid carcinoma (MTC) is an APUDoma (APUD refers to amine precursor uptake and decarboxylation) arising from the parafollicular cells. Diarrhoea has been reported in some 30% of patients, variously attributed to excess production of calcitonin (CT), serotonin (5-HT), vasoactive intestinal peptide (VIP) or other factors. The regulatory factors in MTC were examined employing immunocytochemistry and RIA to tumours and their extracts. The patients were followed up for more than 15 years. CT and calcitonin gene-related peptide were universally expressed in all the tumours. The neuroendocrine markers chromogranin A (and its fragments pancreastatin and WE-14), neurone-specific enolase, protein gene product 9.5 and carcino-embryonic antigen were found in the majority of MTCs and might be useful as immunocytochemical markers. 5-HT, substance P, neurokinin A, glucagon and VIP could not be detected, excluding them as candidates in the diarrhoea of MTC.

111In-octreotide scintigraphy in oncology.

Various tumors of neuroendocrine origin that have amine precursor and decarboxylation (APUD) characteristics can be visualized in vivo after intravenous injection of the somatostatin analogue [123I-Tyr3]-octreotide. However, the relatively short effective half-life of this compound and the high background of radioactivity in the abdomen are drawbacks in its application. Therefore, an 111In-coupled somatostatin analogue ([111In-DTPA-D-Phe1]-octreotide) was developed. This analogue is excreted mainly via the kidneys, 90% of the dose being present in the urine 24 h after injection. Using 111In-octreotide scintigraphy, 7 out of 7 gastrinomas, 4 out of 7 insulinomas, 1 out of 1 glucagonoma, 3 out of 3 unclassified apudomas, but none out of 18 exocrine pancreatic carcinomas were visualized. Also, 19 out of 19 carcinoids, 15 out of 15 glomus tumors, 8 out of 12 medullary thyroid carcinomas, 6 out of 6 small cell lung carcinomas, 4 out of 4 growth hormone-producing and 6 out of 9 clinically nonfunctioning pituitary adenomas were visualized. Apart from APUD-cell-derived tumors, 111In-octreotide scintigraphy was also successfully applied to visualize breast cancer, lymphomas and granulomas. In 39 out of 50 patients with breast carcinoma, 10 out of 11 patients with non-Hodgkin lymphomas, 3 out of 3 patients with Hodgkin's disease, and 8 out of 8 patients with sarcoidosis, tumor sites accumulated radioactivity during octreotide scintigraphy. In a considerable number of patients with carcinoids and glomus tumors, but also in patients with granulomas and lymphomas, 111In-octreotide scintigraphy revealed more tumor sites than did conventional imaging techniques.(ABSTRACT TRUNCATED AT 250 WORDS)