AJCC 2010 TNM Staging & Grouping System

Primary tumor (T) involvement is as follows:

• Tx - Primary tumor cannot be assessed
• T0 - No evidence of tumor
• Tis - Carcinoma in situ
• T1 - Tumor 3 cm or less in greatest dimension, surrounded by lung or visceral pleura, without bronchoscopic evidence of invasion more proximal than the lobar bronchus (not in the main bronchus)
• T1a - Tumor 2 cm or less
• T1b - Tumor more than 2 cm but 3 cm or less
• T2 - Tumor more than 3 cm but 7 cm or less
• T2a - Tumor more than 3 cm but 5 cm or less
• T2b - Tumor more than 5 cm but 7 cm or less
• T3 - Tumor more than 7 cm or one that invades any of the following: parietal pleura, chest wall, diaphragm, phrenic nerve, mediastinal pleura, or parietal pericardium; or tumor in the main bronchus (< 2 cm distal to carina but without involvement of the carina); or associated atelectasis or obstructive pneumonitis of the entire lung or separate tumor nodule in the same lobe 
• T4 - Tumor of any size that invades the following: mediastinum, heart, great vessels, trachea, recurrent laryngeal nerve, esophagus, vertebral body, or carina; separate tumor in a different ipsilateral lobe.

Lymph node (N) involvement is as follows:

• Nx - Regional nodes cannot be assessed
• N0 - No regional node metastasis
• N1 - Metastasis in ipsilateral peribronchial and/or ipsilateral hilar nodes and intrapulmonary nodes, including involvement by direct extension 
• N2 - Metastasis in ipsilateral mediastinal and/or subcarinal node
• N3 - Metastasis in contralateral mediastinal, contralateral hilar, ipsilateral or contralateral scalene node, or supraclavicular node

Metastatic (M) involvement is as follows:

• M0 - No metastasis
• M1 - Distant metastasis
• M1a - Separate tumor nodule in a contralateral lobe tumor with pleural nodules or malignant pleural effusion
• M1b - Distant metastasis

For TNM staging, NSCLC is divided into 4 stages, with further subdivision of stages I-III into A and B subtypes. These stages have important therapeutic and prognostic implications, which are discussed later.

Stage grouping of the TNM system is as follows:

• Stage 0 - TisN0M0
• Stage 1A - T1aN0M0 / T1bN0M0
• Stage 1B - T2aN0M0
• Stage IIA - T2bN0M0 / T1aN1M0 / T1bN1M0 / T1bN1M0 / T2aN1M0
• Stage IIB - T2bN1M0 / T3N1M0
• Stage IIIA - T1aN2M0 / T1bN2M0 / T2aN2M0 / T3N1M0 / T3N2M0 / T4N1M0
• Stage IIIB - T1aN3M0 / T1bN3M0 / T2aN3M0 / T2bN3M0 / T3N3M0 / T4N2M0 / T4N3M0
• Stage IV - Any T, any N, M1a / Any T, any N, M1b
• Pleural or pericardial effusion is M1a not T4
• Separate tumor in the contralateral lung is considered M1a
• M1b designates distant metastases