Improvement in TNM staging of pulmonary neuroendocrine tumors requires histology and regrouping of tumor size Maria Cattoni, MD, a Eric Valli  eres, MD, a Lisa M. Brown, MD, MAS, b Amir A. Sarkeshik, MD, b Stefano Margaritora, MD, c Alessandra Siciliani, MD, c Pier Luigi Filosso, MD, d Francesco Guerrera, MD, d Andrea Imperatori, MD, e Nicola Rotolo, MD, e Farhood Farjah, MD, MPH, f Grace Wandell, MSc, f Kimberly Costas, MD, g Catherine Mann, MD, a Michal Hubka, MD, h Stephen Kaplan, MD, h Alexander S. Farivar, MD, a Ralph W. Aye, MD, a and Brian E. Louie, MD, MHA, MPH a ABSTRACT Objective: Neuroendocrine tumors of the lung are currently staged with the 7th edition TNM non–small cell lung cancer staging system. This decision, based on data analysis without data on histology or disease-specific survival, makes its applicability limited. This study proposes a specific staging system for these tumors. Methods: We retrospectively analyzed 510 consecutive patients (female/male, 313/197; median age, 61 years; interquartile range, 51-70) undergoing lung resection for a primary neuroendocrine tumor between 2000 and 2015 in 8 centers. Multivariable analysis was performed using a Cox proportional hazard model to identify factors associated with disease-specific survival. A new staging system was proposed on the basis of the results of this analysis. Kaplan–Meier disease-specific survival was analyzed by stage using the proposed and the 7th TNM staging system. Results: Follow-up was completed in 490 of 510 patients at a median of 51 months (interquartile range, 18-99). Histology (G1-typical carcinoid vs G2-atypical carci- noid vs G3-large-cell neuroendocrine carcinoma) and pT were independently associated with survival, but pN was not. After regrouping histology and pT, we proposed the following staging system: IA (pT1-2G1), IB (pT3G1, pT1G2), IIA (pT4G1, pT2-3G2, pT1G3), IIB (pT4G2, pT2-3G3), and III (pT4G3). The 5-year survivals were 97.9%, 81.0%, 69.1%, 51.8%, and 0%, respectively. By using the 7th TNM, 5-year survivals were 95.0%, 92.3%, 67.7%, 70.9%, and 65.1% for stage IA, IB, IIA, IIB, and III, respectively. Conclusions: Incorporating histology and regrouping tumor stage create a unique neuroendocrine tumor staging system that seems to predict survival better than the 7th TNM classification. (J Thorac Cardiovasc Surg 2018;155:405-13) A proposed neuroendocrine tumor staging system separates survival curves between stages. Central Message Incorporating histology and regrouping tumor stages create a pulmonary neuroendocrine tumor staging system that seems to predict disease-specific survival better than the AJCC 7th edition TNM. Perspective NETL are a separate entity from NSCLC, yet they are staged with the 7th edition TNM lung cancer system. This limits the utility of staging these tumors. By incorporating the 2 factors that influence disease- specific survival, histology, and tumor stage, a unique NETL staging system can be created to predict sur- vival better than the current system. See Editorial Commentary page 414. See Editorial page 367. Cancer staging systems are designed to provide a common method of evaluating the extent of disease and to predict survival. For common thoracic cancers such as esophageal cancer or non–small cell lung cancer (NSCLC), there is a disease-specific staging system derived from large datasets and multiple outcome studies that allows a reliable and From the a Division of Thoracic Surgery, Swedish Cancer Institute; f Division of Cardiothoracic Surgery, University of Washington Medical Center; h Division of Thoracic Surgery, Virginia Mason Hospital & Seattle Medical Center, Seattle; g Division of Thoracic Surgery, Providence Regional Medical Center, Everett, Wash; b Section of General Thoracic Surgery, Department of Surgery, UC Davis Health, Sacramento, Calif; c Unit of Thoracic Surgery, Catholic University of Sacred Heart, Rome; d Department of Thoracic Surgery, San Giovanni Battista Hos- pital, Torino; and e Center of Thoracic Surgery, Department of Surgical and Morphological Sciences, University of Insubria, Ospedale di Circolo, Varese, Italy. Read at the 97th Annual Meeting of The American Association for Thoracic Sur- gery, Boston, Massachusetts, April 29-May 3, 2017. Received for publication May 4, 2017; revisions received Aug 12, 2017; accepted for publication Aug 25, 2017; available ahead of print Oct 3, 2017. Address for reprints: Brian E. Louie, MD, MHA, MPH, Division of Thoracic Surgery, 900-1101 Madison St, Seattle, WA 98104 (E-mail: brian.louie@swedish.org). 0022-5223/$36.00 Copyright Ó 2017 by The American Association for Thoracic Surgery https://doi.org/10.1016/j.jtcvs.2017.08.102 Scanning this QR code will take you to a supplemental video for the article. The Journal of Thoracic and Cardiovascular Surgery c Volume 155, Number 1 405 THOR Cattoni et al Thoracic: Lung Cancer