TNM 9TH EDNSCLC Lung Cancer Staging
Clinical Staging Assignment
Note: The 9th edition of the TNM staging system for lung cancer was implemented in 2024, providing refined T-descriptors and updated survival data.
Stage Interpretation
Stage IA1
Clinical Framing
Early-stage localized lung cancer. Often eligible for surgical resection or stereotactic radiation (SBRT).
Guidelines & Evidence
Verified
Last Review: 2026
When to Use
Clinical Use
Staging of all Non-Small Cell Lung Cancer (Adenocarcinoma, Squamous Cell, Large Cell).
Used to determine surgical resectability and the need for neoadjuvant or adjuvant systemic therapy.
Initial clinical staging (cTNM) via PET-CT and EBUS/Mediastinoscopy.
How it Works
T (Primary Tumor) Updates
T1: ≤ 3 cm. Subdivided into T1a (≤ 1), T1b (1-2), T1c (2-3).
T2: > 3 to ≤ 5 cm (or involves main bronchus, visceral pleura, or atelectasis).
T3: > 5 to ≤ 7 cm (or invades chest wall, phrenic nerve, or separate nodule in same lobe).
T4: > 7 cm (or invades mediastinum, heart, great vessels, trachea, esophagus, or vertebral body).
N (Regional Nodes) Updates
N0: No nodal metastasis.
N1: Ipsilateral peribronchial/hilar nodes.
N2a: Single N2 station.
N2b: Multiple N2 stations.
N3: Contralateral hilar/mediastinal or supraclavicular nodes.
Clinical Pearls
The N2 Sub-classification
The 9th Edition explicitly separates N2a (single station) from N2b (multiple stations). Single-station N2 disease often remains surgically resectable in a multimodality setting, whereas multi-station N2b disease typically shifts the management toward definitive chemoradiation or Total Neoadjuvant Therapy.
Adjuvant Immunotherapy
For resected Stage IB (T2aN0) to IIIA, modern guidelines now incorporate adjuvant Atezolizumab (if PD-L1 ≥ 1%) or Pembrolizumab (regardless of PD-L1) to improve disease-free survival.
The Evidence
Key Reference
The IASLC Lung Cancer Staging Project: Proposals for the 9th Edition of the TNM Classification for Lung Cancer
IASLC Staging Committee • Journal of Thoracic Oncology. 2024;Clinical update implementing refined survival curves.
Last Comprehensive Review: 2026