1, TX \n 2, T0 No evidence of primary tumour \n 3, Tis Carcinoma in situ \n 4, T1 <= 3 cm, without invasion \n 5, T2 > 3 cm; or involves main bronchus(>2 cm distal to carina)/visceral pleura; or Associated with atelectasis or obstructive pneumonitis that does not involve entire lung \n 6, T3 any size that directly invades any of:chest wall, diaphragm, mediastinal pleura, parietal pericardium; or tumour in main bronchus < 2 cm distal to carina but without involvement of carina; or associated atelectasis or obstructive pneumonitis of entire lung \n 7, T4 any size that invades any of: mediastinum, heart, great vessels, trachea, oesophagus, vertebral body, carina; separate tumour nodule(s) in same lobe; tumour with malignant pleural effusion