Validation Study for the N Descriptor of the Newly Proposed Ninth Edition of the TNM Staging System Proposed by the International Association for the Study of Lung Cancer

In Ha Kim; Geun Dong Lee; Sehoon Choi; Hyeong Ryul Kim; Yong-Hee Kim; Dong Kwan Kim; Seung-Il Park; Jae Kwang Yun

doi:10.1016/j.jtho.2024.04.002

Validation Study for the N Descriptor of the Newly Proposed Ninth Edition of the TNM Staging System Proposed by the International Association for the Study of Lung Cancer

J Thorac Oncol. 2024 Apr 16:S1556-0864(24)00160-6. doi: 10.1016/j.jtho.2024.04.002. Online ahead of print.

Authors

In Ha Kim¹, Geun Dong Lee¹, Sehoon Choi¹, Hyeong Ryul Kim¹, Yong-Hee Kim¹, Dong Kwan Kim¹, Seung-Il Park¹, Jae Kwang Yun²

Affiliations

¹ Department of Thoracic and Cardiovascular Surgery, Asan Medical Center, Ulsan University College of Medicine, Seoul, Republic of Korea.
² Department of Thoracic and Cardiovascular Surgery, Asan Medical Center, Ulsan University College of Medicine, Seoul, Republic of Korea. Electronic address: drjkyun@gmail.com.

PMID: 38614456
DOI: 10.1016/j.jtho.2024.04.002

Abstract

Introduction: The aim of this study was to validate the discriminatory ability and clinical utility of the N descriptor of the newly proposed ninth edition of the TNM staging system for lung cancer in a large independent cohort.

Methods: We retrospectively analyzed patients who underwent curative surgery for NSCLC between January 2004 and December 2019. The N descriptor of patients included in this study was retrospectively reclassified based on the ninth edition of the TNM classification. Survival analysis was performed using the log-rank test and Cox proportional hazard model to compare adjacent N categories.

Results: A total of 6649 patients were included in this study. The median follow-up period was 54 months. According to the newly proposed ninth edition N classification, 5573 patients (83.8%), 639 patients (9.6%), 268 patients (4.0%), and 169 patients (2.5%) were classified into the clinical N0, N1, N2a, and N2b categories and 4957 patients (74.6%), 744 patients (11.2%), 567 patients (8.5%), and 381 patients (5.7%) were classified into the pathologic N0, N1, N2a, and N2b categories, respectively. The prognostic differences between all adjacent clinical and pathologic N categories were highly significant in terms of both overall survival and recurrence-free survival.

Conclusions: We validated the clinical utility of the newly proposed ninth edition N classification for both clinical and pathologic stages in NSCLC. The new N classification revealed clear prognostic separation between all categories (N0, N1, N2a, and N2b) in terms of both overall survival and recurrence-free survival.

Keywords: Lung cancer; N descriptor; Staging; TNM classification.