Malignant pleural mesothelioma (TNM staging)

Below is the eighth edition of the TNM staging system for malignant pleural mesothelioma, which was published in 2018.

T - Tumor
  • Tx: primary tumor cannot be assessed
  • T0: no evidence of primary tumor
  • T1
    • involving ipsilateral parietal pleura (inc. mediastinal and diaphragmatic pleura) +/- visceral pleura
  • T2
    • involving any of the ipsilateral pleural surfaces with at least one of the following features:
      • confluent visceral pleural tumor (including the fissures)
      • involvement of diaphragmatic muscle
      • invasion of the lung parenchyma
  • T3
    • involving all of the ipsilateral pleural surfaces with at least one of the following features:
      • invasion of the endothoracic fascia
      • extension into the mediastinal fat
      • solitary, completely resectable focus invading soft tissues of the chest wall
      • non-transmural involvement of the pericardium
  • T4
    • involving all of the ipsilateral pleural surfaces with at least one of the following features:
      • any rib involvement
      • invasion of the peritoneum through the diaphragm
      • invasion of any mediastinal organ (inc. myocardium)
      • direct extension to the contralateral pleura
      • invasion of the spine or brachial plexus
      • transmural invasion of the pericardium (+/- pericardial effusion)
N - Nodes
  • Nx: nodes cannot be assessed
  • N0: no evidence of nodal involvement
  • N1: ipsilateral bronchopulmonary, hilar, or mediastinal nodal involvement (inc. internal mammary, peridiaphragmatic, pericardial fat pad, or intercostal lymph nodes)
  • N2: contralateral bronchopulmonary, hilar, or mediastinal lymph nodes or ipsilateral or contralateral supraclavicular lymph nodes
M - Metastases
  • Mx: presence of metastases cannot be assessed
  • M0: no evidence of distant metastases
  • M1: distant metastases present

Stage groupings

  • Stage IA: T1, N0, M0
  • Stage IB: T2 or 3, N0, M0
  • Stage II: T1 or 2, N1, M0
  • Stage IIIA: T3, N1, M0
  • Stage IIIB: T1-3, N2, M0 or T4, any N, M0
  • Stage IV: any T, any N, M1

Most Stage I and II tumors are resectable. Some stage III tumors may be resectable.

Previous editions

The seventh edition had separate T1a and T1b categories but these were combined following a survival analysis showing no difference between these two groups . The seventh edition also had an extra category for nodal involvement . Intrapleural (previous N1) and extrapleural (previous N2) lymph nodes are now combined into one category (N1) and previous N3 nodes have been moved into the N2 category.