Gastrointestinal Neuroendocrine Tumors

Neuroendocrine tumors of the gastrointestinal tract are relatively rare neoplasms derived from the diffuse endocrine system (DES), and classified as APUDomas. These neoplasms include mainly pancreatic endocrine tumors (islet cells) and carcinoids. Although malignant, these tumors are often slow-growing. Frequently, these neoplasms secrete hormonal peptides and vasoactive amines that can produce specific endocrine syndromes (islet cell syndromes and carcinoid syndrome). One of the most common symptoms accompanying these syndromes is chronic diarrhea, which can be refractory to standard therapies. Recent advances in understanding the pathophysiology of these tumors have led to better medical therapies for controlling symptoms, diarrhea, and tumor growth. Surgery, chemotherapy, somatostatin analogues, and biologic therapies can all contribute to treatment. This review will cover recent advances in diagnosing and treating these neoplasms and the symptoms they produce.