Table 1.

TNM-8 descriptors for NSCLC (Adapted from Carter et al, 2018 ¹⁰ )

Category	Definition
T
Tx	Primary tumour cannot be assessed, or tumour proven by non-radiological means (sputum or bronchial washings) and cannot be visualised with imaging (or bronchoscopy)
T0	No primary tumour
Tis	Carcinoma in situ (squamous or adenocarcinoma)
T1	Tumour ≤3 cm in greatest dimension
T1a T1b T1c	Tumour ≤1 cm
	Tumour >1 cm but ≤2 cm
	Tumour >2 cm but ≤3 cm
T2	Tumour >3 cm but ≤5 cm or tumour involving the main bronchus (regardless of the distance from the carina), the visceral pleura, with partial or complete lung atelectasis or pneumonitis
T2a T2b	Tumour >3 cm but ≤4 cm in greatest dimension
	Tumour >4 cm but ≤5 cm in greatest dimension
T3	Tumour >5 cm but ≤7 cm in greatest dimension or one that directly invades: parietal pleura, chest wall (including superior sulcus tumours), phrenic nerve, parietal pericardium, or separate tumour nodule or nodules in the same lobe
T4	Tumour measuring >7 cm in greatest dimension or which invades mediastinum, diaphragm, heart, great vessels, trachea, recurrent laryngeal nerve, oesophagus, vertebral body, carina; or separate tumour nodule(s) in a different lobe of ipsilateral lung
N
N0	No regional lymph node metastases
N1	Ipsilateral peribronchial and/or ipsilateral hilar nodes and intrapulmonary nodes, including involvement by direct extension
N2	Ipsilateral mediastinal and/or subcarinal nodes
N3	Contralateral mediastinal, contralateral hilar, scalene, or supraclavicular nodes
M
M0	No distant metastases
M1a	Separate tumour nodule(s) in the contralateral lung, malignant pleural effusion, pleural thickening/nodules or masses, malignant pericardial effusion/ pericardial thickening/nodules/masses
M1b	Single extrathoracic metastasis in a single organ (including non-regional lymph nodes)
M1c	Multiple extrathoracic metastases in a single organ or multiple organs

NSCLC, non-small cell lung cancer.