Table 1 IMIG TNM staging system

T1a

Tumour limited to the ipsilateral parietal including mediastinal and diaphragmatic pleura, no involvement of the visceral pleura

T1b

Tumour involving the ipsilateral parietal including mediastinal and diaphragmatic pleura, scattered foci of tumour also involving the visceral pleura

T2

Tumour involving each of the ipsilateral pleural surfaces (parietal, mediastinal, diaphragmatic and visceral pleura) with at least one of the following features:

• involvement of diaphragmatic muscle

• confluent visceral pleural tumour (including the fissures)

• extension of tumour from visceral pleura into the underlying pulmonary parenchyma

T3

Locally advanced but potentially resectable tumour; tumour involving all of the ipsilateral pleural surfaces (parietal, mediastinal, diaphragmatic and visceral pleura) with at least one of the following features:

• involvement of the endothoracic fascia

• extension into the mediastinal fat

• solitary, completely resectable focus of tumour extending into the soft tissues of the chest wall

• non transmural involvement of the pericardium

T4

Locally advanced technically unresectable tumour; tumour involving all of the ipsilateral pleural surfaces (parietal, mediastinal, diaphragmatic and visceral) with at least one of the following features:

• diffuse extension or multifocal masses of tumour in the chest wall with or without associated rib destruction

• direct transdiaphragmatic extension of tumour to the peritoneum

• direct extension of tumour to the contralateral pleura

• direct extension of tumour to one or more mediastinal organs

• direct extension of tumour into the spine: tumour extending through to the internal surface of the pericardium with or without a pericardial effusion

• tumour involving the myocardium

Lymph nodes (N)

Nx

Regional lymph nodes cannot be assessed

N0

No regional lymph node metastases

N1

Metastases in the ipsilateral bronchopulmonary or hilar lymph nodes

N2

Metastases in the subcarinal or the ipsilateral mediastinal lymph nodes including the ipsilateral internal mammary nodes

N3

Metastases in the contralateral mediastinal, contralateral internal mammary, ipsilateral or contralateral supraclavicular lymph nodes

Metastases (M)

Mx

Presence of distant metastases cannot be assessed

M0

No distant metastasis

M1

Distant metastasis present