Background:  Somatostatin is an inhibitory peptide hormone produced in regions of the brain and by D cells in the gastroenteropancreatic system.  Somatostatin receptors (SSTR) are highly expressed by neuroendocrine neoplasms, especially well-differentiated tumors.  This high-level expression is the basis of nuclear medicine imaging of neuroendocrine tumors (e.g., OctreoScan) and, perhaps more importantly, anti-secretory and anti-proliferative therapy with the somatostatin analogue octreotide.  Of the various receptor subtypes, a positive scan is most closely related to expression of SSTR2A.  Octreotide therapy is only approved in the face of a positive OctreoScan or a positive SSTR2A immunohistochemical result.  Unfortunately, the OctreoScan is usually negative in tumors <2 cm, and occasionally tumors are resected before their neuroendocrine nature is known.

Key Reference:  Korner M, Waser B, Schonbrunn A, Perren A, Reubi JC. Somatostatin receptor subtype 2A immunohistochemistry using a new monoclonal antibody selects tumors suitable for in vivo somatostatin receptor targeting. The American Journal of Surgical Pathology. 2012;36(2):242-52.

The order code in Epic is (LAB8098) and the Cerner Code is ISST2.   Turn-around-time will be 5 days upon receipt of tissue in the laboratory.

Questions concerning testing can be directed to Andrew Bellizzi, MD (6‑4436), or Lisa Horning, MT(ASCP)SI (6‑2688).