Neuroendocrine Tumors of the Gallbladder

Abstract

Gallbladder neuroendocrine tumors (GB-NETs) represent only 0.5% of all NETs, and little is known about their biological behavior. We sought to provide an overview of the current state of knowledge about GB-NETs and provide a recommendation for management. A PubMed search was undertaken using the following criteria: primary gallbladder and carcinoid or NET. We also interrogated the SEER 9, 13 and 17 registries (1973 to 2005) and the Niigata registry (2003) to assess the epidemiology and clinicopathological characteristics. Finally, we compared the clinical presentation, management and prognosis of GB-NETs to that of gallbladder adenocarcinoma. GB-NETs probably derive from either a multipotent stem cell or neuroendocrine cells in intestinal or gastric metaplasia of the gallbladder epithelium, which occurs consequent upon cholelithiasis/chronic inflammation. Clinically and at surgery, GB-NETs are indistinguishable from gallbladder cancer (GBC) and "carcinoid syndrome" is evident in only ∼1%.The median survival was only 9.8 months among 278 cases of GB-NETs reported in SEER. The 5 year survival rate for tumors classified as carcinoids/neuroendocrine carcinoma or small cell cancer (SCC) was 36.9 and 0%, respectively. Soga divided GB-NETs into typical and variant carcinoids with 5 year survival rates of 60.4% and 21.3% respectively. GB-NETs have an aggressive behavior, and once diagnosed, extensive surgical management and careful NET follow up with CT scan is mandatory to facilitate early detection of recurrence. Since more aggressive surgical management for GBC has shown increased survival rates for these tumors, a similar strategy seems reasonable for GB-NETs. However, in high grade metastatic tumors, the primary management is mainly medical.