TNM and Staging of Lung Cancer Simplified

The current staging system is recommended for the classification of both non–small cell and small cell lung carcinomas and for carcinoid tumors of the lung .

TNM Staging of Lung Cancer

Primary Tumor (T)

The “T” staging of bronchogenic carcinoma is a bit complex compared to others. Five things must be checked before assigning a T classification. They can be remembered with a mnemonic: ABCDE.

  1. Atelectasis
  2. Bronchus involvement (bronchoscopy)
  3. Contiguous conquer (Adjacent site invasion)
  4. Diameter in cm
  5. Elevated nodules

Chest wall involvement as in breast cancer denotes advanced T stage.

Diameter (cm)Bronchoscopy (Main bronchus involvement)Atelectasis or Obstructive pneumoniaInvasionNodules
T1A – ≤2 cm
B – 2 to ≤3 cm
T2A – 3 to ≤5 cm≥2 cm distal to carinaLobarVisceral pleura
B – 5 to ≤7 cm
T3>7 cm<2 cm distal to carinaWhole lungChest wall (including pancoast or superior sulcus tumor), Diaphragm, Phrenic nerve, Mediastinal or parietal pleuraSame lung lobe
T4Any sizeCarinaHeart, great vessels, trachea, esophagus, recurrent laryngeal nerve spine,Different ipsilateral lung lobe

lungs lymph nodes

Regional Lymph Nodes (N)

  • N1: Ipsilateral – Peribronchial, hilar or intrapulmonary nodes
  • N2: Ipsilateral – Mediastinal or subcarinal nodes
  • N3:
    • Contralateral – Mediastinal or Hilar (N1 and N2 if ipsilateral)
    • Ipsilateral or Contralateral: Scalene or Supraclavicular nodes

Metastasis (M)


  • a – Separate tumor nodule in contralateral lung lobe (T4 if on ipsilateral lobe), Pleural nodules, Malignant pleural or pericardial effusion
  • b – Distant Metastasis

AJCC Staging of Lung Cancer

lung cancer staging matrix

The staging of lung cancer is similar to another thoracic tumor – breast cancer. In both of these sites, the primary drainage nodes (N1) is close to the involved site, hence, T1=N1.

  • M stage is a separate stage: M1 = Stage IV
  • N stage determines stage group I-III
    • N3 = Stage IIIB
    • N2 = Stage IIIA except with T4 (Stage III B)
  • T stage modifies substages:
    • T4 = Stage IIIB
    • T1 or T2 N0 = Stage IA or IB respectively
    • T1 or T2 N1 = Stage IIA or IIB respectively

Algorithm for Lung Cancer Management


One Viewpoint 💬 on “TNM and Staging of Lung Cancer Simplified”

  1. Great content and information. Knowing the staging of lung cancer and its TNM is very necessary if someone is having doubts about having lung cancer.

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