Analysis of 900 appendiceal carcinoid tumors for a proposed predictive staging system.

Background: 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.

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

Design: 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.

Setting: SEER database study.

Participants: 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.

Results: 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.

Conclusions: 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.