Prognostic Validity of a Novel American Joint Committee on Cancer Staging Classification for Pancreatic Neuroendocrine Tumors

Abstract

Purpose The American Joint Committee on Cancer (AJCC) staging manual (seventh edition) has introduced its first TNM staging classification for pancreatic neuroendocrine tumors (NETs) derived from the staging algorithm for exocrine pancreatic adenocarcinomas. This classification has not yet been validated. Methods Patients with pancreatic NETs treated at the H. Lee Moffitt Cancer Center between 1999 and 2010 were assigned a stage (I to IV) based on the new AJCC classification. Kaplan-Meier analyses for overall survival (OS) were performed based on age, race, histologic grade, incidental diagnosis, and TNM staging (European Neuroendocrine Tumors Society [ENETS] v AJCC) using log-rank tests. Survival time was measured from time of initial diagnosis to date of last contact or date of death. Multivariate modeling was performed using Cox proportional hazards regression. Weighted Cohen's κ coefficient was computed to evaluate the agreement of ENETS and AJCC classifications. Results We identified 425 patients with pancreatic NETs. On the basis of histopathologic grade, 5-year survival rates for low-, intermediate-, and high-grade tumors were 75%, 62%, and 7%, respectively (P < .001). When using the ENETS classification, 5-year OS rates for stages I, II, III, and IV were 100%, 88%, 85%, and 57%, respectively (P < .001). Subsequently, using the AJCC classification, 5-year OS rates for stages I, II, III, and IV were 92%, 84%, 81%, and 57%, respectively (P < .001). Both the novel AJCC classification and the ENETS classification were highly prognostic for survival. Conclusion The AJCC TNM classification for pancreatic NETs is prognostic for OS and can be adopted in clinical practice.