WCLC 2025 - Posters & ePosters-P3.13.17 A Comparative Analysis of TNM 8 and TNM 9 Classification Systems in Small Cell Lung Cancer

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This study presents a retrospective analysis comparing the 8th (TNM8) and 9th (TNM9) editions of the TNM lung cancer staging system in small cell lung cancer (SCLC) patients treated at the Karolinska Comprehensive Cancer Center between 2016 and 2022. The TNM classification, traditionally developed for non-small cell lung cancer (NSCLC), has limited applicability in SCLC, motivating evaluation of the updated TNM9 system for improved prognostic accuracy.<br /><br />A total of 421 SCLC patients were assessed, with 58% female and a median age distribution slightly favoring those over 70 years. Most patients were current or former smokers, and treatments included chemotherapy-immunotherapy (74%), radio-chemotherapy (9.5%), surgery (rarely), and best supportive care. Imaging was performed with CT (65%) or PET-CT (35%).<br /><br />Key changes from TNM8 to TNM9 involved subclassifying N2 nodal involvement and M1c metastatic disease. N2 in TNM8 described ipsilateral mediastinal/subcarinal nodal involvement without distinction; TNM9 subdivides into N2a (single region) and N2b (multiple regions). Similarly, M1c metastatic disease is divided in TNM9 into M1c1 (single organ) and M1c2 (multiple organs).<br /><br />Statistical analysis using multivariate Cox regression adjusted for age, sex, and performance status showed that the TNM9 subcategories N2b and M1c2 were independent negative prognostic factors associated with shorter overall survival (hazard ratios around 1.5 and 1.3, respectively). This subclassification thus identified clinically relevant risk groups within SCLC patients that were not captured by TNM8.<br /><br />The study concludes that TNM9 classification improves stage stratification and prognostic discrimination in SCLC compared to TNM8. Incorporating the N2 and M1c subcategories may enhance clinical decision-making and risk assessment in this patient population.

Asset Subtitle

Asaf Dan

Meta Tag

Speaker Asaf Dan

Topic Small Cell Lung Cancer and Neuroendocrine Tumors

Keywords

small cell lung cancer

SCLC

TNM staging system

TNM8

TNM9

N2 nodal subclassification

M1c metastatic subclassification

prognostic factors

Karolinska Comprehensive Cancer Center

lung cancer treatment