Somatostatin analogs in the treatment of neuroendocrine gastroenteropancreatic and intrathoracic tumors.

Somatostatin is a peptide hormone that posses several biological functions of which inhibition of hormone secretion from endocrine cells is one. Neuroendocrine tumors usually express somatostatin receptors (SSTRs), although the subtypes and number of SSTRs expressed in a certain tumor is very variable. The primary goal of somatostatin analog treatment is to decrease hormone production and secretion, resulting in control of hormone induced symptoms, while the ability of somatostatin analogs to retard tumor growth is less well documented. All patients considered for somatostatin analog treatment should undergo SSTR scintigraphy (111In-pentetreotide) to establish SSTR status, since the expression is usually correlated to therapeutic response. By this approach, it is possible to select patients suitable for treatment. Among patients with functioning neuroendocrine tumors expressing SSTR, more than 80% respond with symptomatic relief during somatostatin analog treatment, while treatment of non-functioning tumors still remains somewhat controversial.