Relapse-free survival in patients with nonmetastatic, surgically resected pancreatic neuroendocrine tumors: an analysis of the AJCC and ENETS staging classifications.

BACKGROUND: The risk of metastatic spread among patients with early-stage pancreatic neuroendocrine tumors has not been well established. The authors sought to evaluate whether the new TNM staging systems proposed by the American Joint Committee on Cancer (AJCC) and European Neuroendocrine Tumor Society (ENETS) are prognostic for relapse-free survival (RFS) after surgical resection.
METHODS: Patients with surgically resected localized or locally advanced pancreatic NETs treated at the H. Lee Moffitt Cancer Center between 1999 and 2010 were assigned a stage (I-III) based on the AJCC and ENETS classifications. RFS and overall survival were measured using Kaplan-Meier methodology, with log-rank testing for evaluation of the 2 tumor staging systems. Multivariate analysis was performed controlling for tumor grade, location, surgery type, functional hormonal status, and incidental diagnosis.
RESULTS: The authors identified 123 patients with nonmetastatic, surgically resected pancreatic NETs. When using the AJCC classification, 5-year RFS rates for stages I through III were 78%, 53%, and 33%, respectively (P < 0.01). Using the ENETS classification, 5-year RFS rates for stages I to III were 100%, 70%, and 53% (P < 0.18). When excluding patients who were referred after their metastatic recurrence, the 5-year RFS rates for stages I to III were 90%, 73%, and 66% according to the AJCC classification, and 100%, 84%, and 75% according to the ENETS classification. Recurrence rates peaked at approximately 2 years after surgery.
CONCLUSIONS: The AJCC and ENETS TNM classifications for pancreatic NETs are prognostic for recurrence-free survival and can be adopted in clinical practice.