WCLC 2025 - Posters & ePosters-PT1.05.03 Comparison Between Lymph Node Station- and Zone-Based Classification: Analysis With the 9th IASLC Node Descriptors in Surgically Resected NSCLC

PT1.05.03 Comparison Between Lymph Node Station- and Zone-Based Classification: Analysis With the 9th IASLC Node Descriptors in Surgically Resected NSCLC

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This study from Asan Medical Center assessed lymph node (LN) classifications in non-small cell lung cancer (NSCLC) under the 9th IASLC TNM staging system, comparing the traditional station-based approach to a zone-based classification that groups adjacent LN stations into broader anatomical zones. This analysis included 11,047 surgically resected NSCLC patients from 2005 to 2022, excluding those with residual tumors, preoperative therapy, certain metastases, or incomplete lymph node dissection.<br /><br />Key findings include:<br /><br />- Both classification systems significantly stratified overall survival (OS) and freedom from recurrence (FFR).<br />- Among patients classified as station-based N2b (multiple LN stations involved), 28.8% were reclassified as zone-based N2a (single zone involvement). Survival within the zone-based N2a group was similar regardless of original station-based classification.<br />- Conversely, patients reclassified from station-based N2b to zone-based N2a had significantly worse survival compared to those remaining zone-based N2b, indicating better prognostic discrimination using zones.<br />- Multivariable Cox regression confirmed both systems independently predicted OS and FFR, but statistical measures (AIC, R², Harrell’s C-index) slightly favored the zone-based classification.<br />- Zone-based classification reduces ambiguity from anatomical overlap in LN stations and better reflects tumor biology, especially important in N2 disease where prognosis and treatment decisions are challenging.<br /><br />Concluding, the zone-based LN classification offers clearer prognostic stratification in NSCLC than the station-based system. Incorporation of zone-based descriptors could enhance future TNM staging revisions and improve clinical decision-making by more accurately reflecting lymphatic spread patterns and associated outcomes in NSCLC patients.

Asset Subtitle

Shia Kim

Meta Tag

Speaker Shia Kim

Topic Pulmonology and Staging

Keywords

non-small cell lung cancer

NSCLC

lymph node classification

IASLC TNM staging

station-based classification

zone-based classification

overall survival

freedom from recurrence

prognostic stratification

lymphatic spread