Revised nodal stage for pancreatic neuroendocrine tumors

Background: Previously we have proposed a modified European Neuroendocrine Tumor Society (mENETS) staging system for pNETs, which is more suitable than either the American Joint Committee on Cancer (AJCC) or the European Neuroendocrine Tumor Society (ENETS) systems. However, it is necessary to revise the nodal stage of the mENETS system for the under representation of stage III diseases. Methods: Nodal substages of the upper gastrointestinal organs (N0: 0 node, N1: 1-2 nodes; N2: >= 3 nodes) or the lower gastrointestinal organs (0: 0 node, N1: 1-3 nodes, and N2: >= 4 nodes) were incorporated into the mENETS system and evaluated using the Surveillance, Epidemiology, and End Results (SEER) registry series. Results: The mENETS classification with the upper gastrointestinal N-stage revision (stage III, 17.1%) had better proportional distribution than the mENETS classification (stage III, 8.7%) or the lower gastrointestinal N-stage revision (stage III, 14.5%). N-stage revision (N0: 0 node, N1: 1-2 nodes; N2: >= 3 nodes) was incorporated in the mENETS staging definition for further analysis. Survival curves were well separated by nodal substages. HRs of stage IIA (T3N0M0) and IIB (T1-3N1M0) of the mENETS classification with N-stage revision were similar, indicating these two substages should be attributed to stage II. Survival curves were well separated by stage using the mENETS classification with N-stage revision. Conclusions: The mENETS classification with N-stage revision (N0: 0 node, N1: 1-2 nodes; N2: >= 3 nodes) had better prognostic value and proportional distribution than the mENETS classification for pNETs and can be used in clinical practice. (C) 2017 Published by Elsevier B.V. on behalf of 1AP and EPC.