The expanding role of somatostatin analogs in gastroenteropancreatic and lung neuroendocrine tumors.

Somatostatin analogs (SSAs) were initially developed as antisecretory agents used for the control of hormonal syndromes associated with neuroendocrine tumors (NETs). In recent years, accumulating evidence has also supported their role as antiproliferative agents in well or moderately differentiated NETs. The phase III PROMID trial demonstrated that octreotide long-acting repeatable (LAR) can significantly prolong time to progression among patients with metastatic midgut NETs. More recently, the randomized CLARINET trial reported a significant improvement in progression-free survival in a heterogeneous population of patients with gastroenteropancreatic (GEP)-NETs treated with depot lanreotide. Octreotide and lanreotide target somatostatin receptor subtypes in a similar fashion, and appear to be clinically interchangeable; however, comparative noninferiority trials have not been performed. Further studies are needed to evaluate the efficacy of novel SSAs such as pasireotide in the refractory setting, and the role of high-dose SSAs for symptom and tumor control.