The 7th lung cancer TNM classification and staging system: Review of the changes and implications

Table 1 Seventh tumour, node, metastasis classification of lung cancer: January 2010 [10]

T: Tumour
TX	Primary tumour cannot be assessed, or tumour proven by the presence of malignant cells in sputum or bronchial washings but not visualized 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)
T1a	Tumour < 2 cm in greatest dimension
T1b	Tumour > 2 cm but < 3 cm in greatest dimension
T2	Tumour > 3 cm but < 7 cm or tumour with any of the following features (T2 tumours with these features are classified T2a if < 5 cm):
	Involves main bronchus, > 2 cm distal to the carina
	Invades visceral pleura
	Associated with atelectasis or obstructive pneumonitis that extends to the hilar region but does not involve the entire lung
T2a	Tumour > 3 cm but < 5 cm in greatest dimension
T2b	Tumour > 5 cm but < 7 cm in greatest dimension
T3	Tumour > 7 cm or one that directly invades any of the following:
	Chest wall (including superior sulcus tumours), diaphragm, phrenic nerve, mediastinal pleura, parietal pericardium
	Tumour in the main bronchus < 2 cm distal to the carina but without involvement of the carina
	Associated atelectasis or obstructive pneumonitis of the entire lung
	Separate tumour nodule(s) in the same lobe
T4	Tumour of any size that invades any of the following:
	Mediastinum, heart, great vessels, trachea, recurrent laryngeal nerve, esophagus, vertebral body, carina
	Separate tumour nodule(s) in a different ipsilateral lobe
N: Nodes
NX	Regional lymph nodes cannot be assessed
N0	No regional lymph node metastasis
N1	Metastasis in ipsilateral peribronchial and/or ipsilateral hilar lymph nodes and intrapulmonary nodes, including involvement by direct extension
N2	Metastasis in ipsilateral mediastinal and/or subcarinal lymph node(s)
N3	Metastasis in contralateral mediastinal, contralateral hilar, ipsilateral or contralateral scalene, or supraclavicular lymph node(s)
M: Metastases
MX	Distant metastasis cannot be assessed
M0	No distant metastasis
M1	Distant metastasis
M1a	Separate tumour nodule(s) in a contralateral lobe
	tumour with pleural nodules or malignant pleural/ pericardial effusion
M1b	Distant metastasis

Table 2 Summary of what has changed

Feature	Old - sixth classification 2002-2009	Current, new - seventh classification - Jan 2010
Tumour < 2 cm	T1	T1a
Tumour > 2 but < 3 cm	T1	T1b
Tumour > 3 cm but < 5 cm	T2	T2a
Tumour > 5 but < 7 cm	T2	T2b
Tumour > 7 cm	T2	T3
Tumour - same lobe nodules	T4	T3
Ipsilateral lung nodule - non primary lobe	M1	T4
Malignant pleural effusion	T4	M1a
Contralateral lung nodule	M1	M1a
Distant metastases	M1	M1b

Table 3 Changes in the staging of lung cancer based on the new tumour, node, metastasis classification: Cells in the bold indicate a change from the sixth edition for a tumour, node, metastasis category[10]

Old- sixth edition- descriptor	New seventh edition-descriptor	N0	N1	N2	N3
T1 ( ≤ 2 cm)	T1a	I A	II A	III A	III B
T1 (> 2-3 cm)	T1b	I A	II A	III A	III B
T2 ( ≤ 5 cm)	T2a	I B	II A	III A	III B
T2 (> 5-7 cm)	T2b	II A	II B	III A	III B
T2 (> 7 cm)	T3	II B	III A	III A	III B
T3 (invasion)	T3	II B	III A	III A	III B
T4 (same lobe nodule)	T3	II B	III A	III A	III B
T4 (extension)	T4	III A	III A	III B	III B
M1 (ipsilateral non primary lobe nodule)	T4	III A	III A	III B	III B
T4 (pleural effusion)	M1a	IV	IV	IV	IV
M1 (contralateral lung nodule)	M1a	IV	IV	IV	IV
M1 (distant metastases)	M1b	IV	IV	IV	IV