Appendiceal carcinoid tumors (ACTs) are rare, and little is known about the long-term prognosis for these tumors because no staging system exists. Therefore, we sought to investigate prognostic factors associated with ACTs and to create a predictive staging system to accurately estimate prognosis.

In patients with ACTs, TNM staging will accurately predict prognosis.

Retrospective review of 15 983 patients with carcinoid tumors in the Surveillance Epidemiology and End Results (SEER) database from January 1, 1977, to December 31, 2004.

SEER database study.

Nine hundred patients with ACTs (552 females and 348 males; mean age, 47.1 years [age range, 9-89 years]; mean size of the primary tumor, 2.4 cm [range, 0.1-11.5 cm]). Main Outcome Measure Clinicopathologic features in patients with ACTs that affect prognosis using a newly created TNM staging system incorporating these parameters.

Lymph node metastasis was found in 137 patients (24%), and distant metastatic disease in 89 patients (10%). Stage-specific survival was statistically significant between stages (P < .001) but not within stages. At multivariate analysis, patient age, primary tumor size, histologic features, lymph node involvement, and distant metastasis were significant factors predicting survival.

Our newly developed TNM staging system accurately predicts prognosis in patients with ACTs. A TNM staging system for ACTs will be helpful not only for physician education about factors that affect the outcome with this disease but also to observe trends in prognosis.