TNM Staging of Lung cancer

Tumor size (T):

Tx: Primary tumor not able to be assessed
T0: No evidence of primary tumor, i.e.. cancer cells seen on sputum sampling or bronchial washing only
Tis: Carcinoma in situ
T1: Tumor 3 cm or less, surrounded by pleura, without evidence of invasion more proximal than the lobar bronchus.
T2: Tumor with any of the following features:
>3 cm in greatest dimension
Involves main bronchus, 2 cm or more distal to the carina
Invades visceral pleura
Associated with atelectasis or obstructive pneumonitis, extending to the hilar region but not involving the entire lung.
T3: Tumor of any size,
directly invading the chest wall, diaphragm, mediastinal pleura or parietal pericardium; or tumor in the main bronchus; or
in the main bronchus, less than 2 cm distal to the carina, but without involvement of the carina; or
with associated atelectasis or obstructive pneumonitis of the entire lung
T4: Tumor of any size, invading the mediastinum, heart, great vessels, trachea, oesophagus, vertebral body, carina; or with separate tumor nodules in one lobe, or with malignant pleural effusion

Lymph Nodes (N):

NX: Regional lymph nodes not able to 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 nodes
N3: Metastasis in contralateral mediastinal, contralateral hilar, ipsilateral or contralateral scalene, or supraclavicular lymph nodes

Metastasis (M)

MX: Distant metastasis not able to be assessed
M0: No distant metastasis
M1: Distant metastasis, including separate tumor nodule(s) in a different lobe (ipsi- or contralateral).

Using this classification, non-small cell lung cancers are grouped into stages as follows:
Stage 0: TIS N0 M0
Stage Ia: T1 N0 M0
Stage Ib: T2 N0 M0
Stage IIa: T1 N1 M0
Stage IIb: T2 N1 M0, T3 N0 M0
Stage IIIa: T1 N2 M0, T2 N2 M0, T3 N1 M0, T3 N2 M0
Stage IIIb: any T N3 MO, T4 any N M0
Stage IV: any T any N M1