The International Mesothelioma Interest Group Staging System for malignant pleural mesothelioma
| T | |
| T1 | Tumour of the ipsilateral parietal pleura, including diaphragm and mediastinal pleura |
| T1a | No visceral pleural involvement |
| T1b | With visceral pleural involvement |
| T2 | Tumour affecting parietal, visceral, diaphragmatic and mediastinal pleura, with either involvement of diaphragmatic muscles or pulmonary parenchyma |
| T3 | Involvement of the endothoracic fascia, extension into the mediastinal fat, non-transmural involvement of the pericardium or resectable focus of chest wall invasion |
| T4 | Unresectable disease, diffuse chest wall or mediastinal involvement, direct transdiaphragmatic spread into the peritoneum, contralateral plural involvement, invasion of the spine, ribs or brachial plexus, trans-mural pericardial invasion or malignant pericardial effusion |
| N | |
| N0 | No regional lymph node metastases |
| N1 | Metastases in ipsilateral bronchopulmonary or hilar lymph nodes |
| N2 | Metastases in subcarinal or ipsilateral mediastinal lymph nodes, including ipsilateral internal mammary chain |
| N3 | Contralateral lymph node metastases, ipsilateral or contralateral supraclavicular lymph node involvement, and scalene nodes |
| M | |
| M0 | No extrathoracic metastases |
| M1 | Extrathoracic metastases present |
Reproduced from [41] with permission from the publisher.