Treatment of Appendiceal Neuroendocrine Tumors

Approximately 90% of appendiceal neuroendocrine (carcinoid) tumors measure smaller than 1 cm and are not located in the appendiceal base. These tumors can be consistently cured by appendectomy.[1]

Appendiceal neuroendocrine tumors larger than 2 cm require right-sided hemicolectomy and ileocecal lymphadenectomy because of the significant risk of metastasis.[1] For tumors measuring 1 to 2 cm, treatment is controversial, but hemicolectomy may be appropriate if there is invasion in the mesoappendix, if there is residual tumor in the resection margins, or in the presence of lymph node metastases. For same-size lesions confined to the appendiceal wall, appendectomy alone may carry a low risk for metastases. Acceptable indications for hemicolectomy may include operative specimens that show high proliferative activity (high Ki-67 index), high mitotic index, or signs of angioinvasion, but evidence is limited and histological parameters for risk evaluation in appendiceal neuroendocrine tumors measuring 1 cm to 2 cm requires definition.[1-3] Follow-up should be considered in patients for whom elevated serum chromogranin A may indicate the need for extended operation. Although survival is excellent with locoregional tumor, 10-year survival is approximately 30% with distant metastases.[1]

Goblet cell carcinoid or adenocarcinoid is a rare variant of appendiceal neuroendocrine tumor with mixed endocrine and exocrine features.[1] Often presenting with a diffusely inflamed appendix and occurring in patients at a later age (~50 years), these tumors are aggressive, often with peritoneal and ovarian metastases, and occasionally appearing as mucinous adenocarcinoma.[2-4] They do not express somatostatin receptors and cannot be visualized by indium In 111-octreotide scintigraphy. Goblet cell carcinoids are treated with right-sided hemicolectomy and lymphadenectomy in combination with chemotherapy. For disseminated tumors, aggressive surgical reduction including peritonectomy and oophorectomy may be required.[1] Goblet cell carcinoids have a 10-year survival rate of approximately 60%.[2]