The following are the TNM definitions for non-small cell lung cancer adopted by the UICC and AJCC in 1997. These tumours are then grouped into Stages I ,II, III and IV (see diagram below).

Primary tumor (T)

TX: Primary tumor cannot be assessed, or tumor 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: A tumour that is 3 cm or less in greatest dimension, surrounded by lung or visceral pleura, and without bronchoscopic evidence of invasion more proximal than the lobar bronchus (i.e., not in a main bronchus)*

T2: A tumour with any of the following features of size or extent:

1. •More than 3 cm in greatest dimension
   

2. •Involves a main bronchus, 2 cm or more distal to the carina
   

3. •Invades the visceral pleura
   

4. •Associated with atelectasis or obstructive pneumonitis that extends to the hilar region but does not involve the entire lung
   

T3: A tumour of any size that directly invades any of the following:

1. •chest wall (including superior sulcus tumours), diaphragm, mediastinal pleura (or phrenic nerve), parietal pericardium; or
   

2. •tumour in the main bronchus less than 2 cm distal to the carina but without involvement of the carina; or
   

3. •associated atelectasis or obstructive pneumonitis of the entire lung
   

T3a: atelectasis or obstructive pneumonitis of one entire lung without other criterion for T3.

T3b: Other criterion present for T3

T4: A tumour of any size that invades any of the following:

1. •mediastinum, heart, great vessels, trachea, oesophagus, recurrent laryngeal nerve, vertebral body, carina; or
   

2. •separate tumour nodules in the same lobe; or
   

3. •tumour with a malignant pleural effusion **
   

T4a: all T4 except T4b

T4b: invasion of the carina or presence of a malignant pleural effusion

*Note: 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 as T1.

**Note: Most pleural effusions associated with lung cancer are due to tumour. However, there are a few patients in whom multiple cytopathologic examinations of pleural fluid are negative for tumour. In these cases, fluid is non-bloody and is not an exudate. 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 and the patient should be staged as T1, T2, or T3.

Regional lymph nodes (N)

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 including involvement by direct extension of the primary tumour

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

1. •N2a: Metastases in ipsilateral mediastinal nodes other than the paratracheal or para-oesophageal nodes
   

2. •N2b: Metastases in the paratracheal and para-oesophageal nodes
   

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

1. •N3a: Metastases in the contralateral (hilar or mediastinal) nodes
   

2. •N3b: Metastases in the supra-clavicular fossae or scalene nodes
   

Distant metastasis (M)

MX: Distant metastasis cannot be assessed

M0: No distant metastasis

M1: Distant metastasis present

Note: M1 includes separate tumour nodule(s) in a different lobe (ipsilateral or contralateral).

Specify sites according to the following notations:

BRA = brain EYE = eye HEP = hepatic

LYM = lymph nodes MAR = bone marrow OSS = osseous

OTH = other OVR = ovary PER = peritoneal

PLE = pleura PUL = pulmonary SKI = skin