Primary tumour (T-factor)

TX       Primary tumour cannot be assessed, or tumour proven by the presence of malignant cells in sputum or bronchial washings but not visualised by imaging or bronchoscopy

T0        No evidence of primary tumour

Tis            Carcinoma in situ

T1        Tumour <3 cm in greatest dimension, surrounded by lung or visceral pleura, without bronchoscopic evidence of invasion more proximal than the lobar bronchus (i.e. not in the main bronchus)*

T2        Tumour with any of the following features of size or extent: >3 cm in greatest dimension, involves main bronchus, >2 cm distal to the carina, invades the visceral pleura, associated with atelectasis or obstructive pneumonitis that extends to the hilar region but does not involve the entire lung

T3        Tumour of any size that directly invades any of the following: chest wall (including superior sulcus tumours), diaphragm, mediastinal pleura, parietal pericardium; or tumour in the main bronchus <2 cm distal to the carina, but without involvement of the carina; or associated atelectasis or obstructive pneumonitis of the entire lung

T4        Tumour of any size that invades any of the following: mediastinum, heart, great vessels, trachea, oesophagus, vertebral body, carina; or tumour with a malignant pleural or pericardial effusion**; or tumour with satellite tumour nodule(s) within the ipsilateral primary-tumour lobe of the lung

^* : The uncommon superficial tumour of any size with its invasive component limited to the bronchial wall, which may extend proximal to the main bronchus, is also classified T1.

^** :Most pleural effusions associated with lung cancer are due to tumour. However, there are a few patients in whom multiple pathologic examinations of pleural fluid show no tumour. In these cases, the fluid is non-bloody and is not an exsudate. When these elements and clinical judgement dictate that the effusion is not related to the tumour, the effusion should be excluded as a staging element.

Regional lymph nodes (N-factor)

NX            Regional lymph nodes cannot be assessed

N0       No regional lymph node metastasis

N1            Metastasis to ipsilateral peribronchial and/or ipsilateral hilar lymph nodes, and intrapulmonary nodes involved by direct extension of the primary tumour

N2            Metastasis to ipsilateral mediastinal and/or subcarinal lymph node(s)

N3            Metastasis to contralateral mediastinal, contralateral hilar, ipsilateral or contralateral scalene, or supraclavicular lymph node(s)

Distant metastasis (M-factor)

MX            Presence of distant metastasis cannot be assessed

M0      No distant metastasis

M1      Distant metastasis present (separate metastatic tumour nodule(s) in the ipsilateral non-primary-tumour lobe(s) of the lung also are classified M1)