Varying malignant potential of appendiceal neuroendocrine tumors: Importance of histologic subtype

Background Neuroendocrine tumors (NETs) of the appendix include malignant carcinoid tumor (MCT), goblet cell carcinoid (GCT), and composite goblet cell carcinoid-adenocarcinoma (CGCC-A). Methods We compared characteristics and outcomes of these histologic subtypes. Patients with appendiceal NETs were identified from the National Cancer Database (19982007). Descriptive statistics were used to compare cohorts and associations between clinicopathologic factors and overall survival (OS) were examined using Cox proportional hazards models. Results A total of 2,812 patients with appendiceal NETs were identified. The most common histologic subtype was GCT (59.6%), followed by MCT (32.1%), CGCC-A (6.9%), and others (1.4%). CGCC-A had a significantly higher incidence of lymph node metastases (odds ratio [OR], 3.2; 95% confidence interval [CI], 2.14.8) and distant metastases (OR, 6.0; 95% CI?=?3.89.3) than GCT. The 5-year OS was 86.3% (95% CI, 81.489.9) for MCT, 77.6% (95% CI, 74.080.8) for GCT, and 56.3% (95% CI, 42.168.4) for CGCC-A (P?<?0.0001). Conclusion Appendiceal NETs represent a spectrum of disease with varying malignant potential: MCT (low), GCT (intermediate), and CGCC-A (high). GCTs represent the most common subtype, whereas CGCC-As place the patient at highest risk for regional and distant metastases and have the worst prognosis. J. Surg. Oncol. 2013;107:136143. (c) 2012 Wiley Periodicals, Inc.