The Role of Somatostatin and Its Analogs in the Diagnosis and Treatment of Tumors

Abstract

LONG-term therapy with somatostatin analogs has been reported to result in the control of hormonal hypersecretion, in improvement of symptomatology, and in tumor shrinkage in patients with acromegaly, endocrine pancreatic tumors, and metastatic carcinoids. One of these somatostatin analogs, octreotide, has been approved for clinical use in most countries, including the United States. It is a well-tolerated, but expensive drug. Experimental studies show that chronic administration of somatostatin analogs causes growth inhibition of a number of (transplantable) tumors in animals, including chondrosarcomas, pancreatic, prostatic, breast, and pituitary cancers. Somatostatin receptors have been demonstrated on a variety of human tumors by classical biochemical binding techniques, as well as by in vitro autoradiography. These tumors include those with amine precursor uptake and decarboxylation (APUD) characteristics (pituitary tumors, endocrine pancreatic tumors, carcinoids, paragangliomas, small cell lung cancers, medullary thyroid carcinomas, pheochromocytomas), as well as meningiomas, well-differentiated brain tumors (astrocytomas), neuroblastomas, and some human breast cancers. Recently we developed a technique that allows the in vivo visualization in man of the somatostatin receptorpositive tumors mentioned above after the iv administration of the 123I-coupled somatostatin analog Tyr3-octreotide. We have simplified, as well as improved, this technique, which should be available for general use in 1992.