LUNG (ICD‐O C34)

Rules for Classification

The classification applies to carcinomas of the lung, including non‐small cell carcinomas, small cell carcinomas and bronchopulmonary carcinoid tumours. It does not apply to sarcomas and other rare tumours.

There should be histological confirmation of the disease and division of cases by histological type.

Anatomical Subsites

Main bronchus (C34.0)
Upper lobe (C34.1)
Middle lobe (C34.2)
Lower lobe (C34.3)

Regional Lymph Nodes

The regional lymph nodes are the intrathoracic nodes (mediastinal, hilar, lobar, interlobar, segmental and subsegmental), scalene and supraclavicular lymph nodes.

TNM Clinical Classification

T – Primary Tumour

TX	Primary tumour cannot be assessed, or tumour proven by the presence of malignant cells in sputum or bronchial washings, but not visualized by imaging or bronchoscopy
T0	No evidence of primary tumour
Tis (AIS)	Adenocarcinoma in situ (Fig. 266)
Tis (SCC)	Squamous cell carcinoma in situ
T1	Tumour 3 cm or less in greatest dimension, surrounded by lung or visceral pleura, without bronchoscopic evidence of invasion more proximal than the lobar bronchus (i.e., not in the main bronchus)¹
	T1mi	Minimally invasive adenocarcinoma (Fig. 266)
	T1a	Tumour 1 cm or less in greatest dimension (Fig. 266)
	T1b	Tumour more than 1 cm but not more than 2 cm in greatest dimension (Fig. 267)
	T1c	Tumour more than 2 cm but not more than 3 cm in greatest dimension (Fig. 267)
T2	Tumour more than 3 cm but not more than 5 cm; or tumour with any of the following features:² Involves main bronchus regardless of distance to the carina, but without involving the carina Invades visceral pleura (Fig. 268) Associated with atelectasis or obstructive pneumonitis that extends to the hilar region, either involving part of the lung or the entire lung
	T2a	Tumour more than 3 cm but not more than 4 cm in greatest dimension (Fig. 269)
	T2b	Tumour more than 4 cm but not more than 5 cm in greatest dimension (Fig. 269)
T3	Tumour more than 5 cm but not more than 7 cm in greatest dimension or one that directly invades any of the following: chest wall (including superior sulcus tumours), phrenic nerve, parietal pericardium; or associated separate tumour nodule(s) in the same lobe as the primary (Fig. 270)
T4	Tumours more than 7 cm (Fig. 271) or one that invades any of the following: diaphragm (Fig. 272), mediastinum, heart (Figs. 272, 273), great vessels (Figs. 272, 274, 275), trachea, recurrent laryngeal nerve, oesophagus (Fig. 276), vertebral body (Fig. 277), carina; separate tumour nodule(s) in a different ipsilateral lobe to that of the primary (Fig. 271)

In tumour masses, grey colour means part‐solid/non‐invasive tumour; black colour means solid/invasive tumour.

Schematic illustration of Adenocarcinoma in situ, Minimally invasive adenocarcinoma and Tumour 1 cm or less in greatest dimension. — **Fig. 266**

Schematic illustration of tumour more than 1 cm but not more than 2 cm in greatest dimension. — **Fig. 267**

Schematic illustration of Involves main bronchus regardless of distance to the carina, but without involving the carina, Invades visceral pleura. — **Fig. 268**

Schematic illustration of tumour more than 3 cm but not more than 4 cm in greatest dimension. — **Fig. 269**

Schematic illustration of tumour more than 5 cm but not more than 7 cm in greatest dimension or one that directly invades any of the following: chest wall (including superior sulcus tumours), phrenic nerve, parietal pericardium; or associated separate tumour nodule(s) in the same lobe as the primary. — **Fig. 270**

Schematic illustration of tumours more than 7 cm. — **Fig. 271**

Schematic illustration of diaphragm. — **Fig. 272**

Schematic illustration of mediastinum, heart. — **Fig. 273**

Schematic illustration of great vessels. — **Fig. 274**

Schematic illustration of trachea, recurrent laryngeal nerve, oesophagus. — **Fig. 276**

Schematic illustration of vertebral body. — **Fig. 277**

N – Regional Lymph Nodes

NX	Regional lymph nodes cannot be assessed
N0	No regional lymph node metastasis
N1	Metastasis in ipsilateral peribronchial, ipsilateral interlobar and/or ipsilateral hilar lymph nodes and Intrapulmonary nodes, including involvement by direct extension (Figs. 278, 279)
N2	Metastasis in ipsilateral mediastinal and/or subcarinal lymph node(s) (Fig. 280)
N3	Metastasis in contralateral mediastinal, contralateral hilar, ipsilateral or contralateral scalene, or supraclavicular lymph node(s) (Fig. 281)

Schematic illustration of Metastasis in ipsilateral peribronchial, ipsilateral interlobar and ipsilateral hilar lymph nodes and Intrapulmonary nodes, including involvement by direct extension. — **Fig. 278**

Schematic illustration of Metastasis in ipsilateral mediastinal and subcarinal lymph node. — **Fig. 280**

Schematic illustration of Metastasis in contralateral mediastinal, contralateral hilar, ipsilateral or contralateral scalene, or supraclavicular lymph node. — **Fig. 281**

M – Distant Metastasis

M0	No distant metastasis
M1	Distant metastasis
	M1a	Separate tumour nodule(s) in a contralateral lobe (Fig. 282); tumour with pleural or pericardial nodules or malignant pleural (Fig. 283) or pericardial effusion (Fig. 284)³
	M1b	Single extrathoracic metastasis in a single organ (Figs. 285, 286)
	M1c	Multiple extrathoracic metastases in a single or multiple organ(s) (Fig. 287)

Schematic illustration of Separate tumour nodule(s) in a contralateral lobe. — **Fig. 282**

Schematic illustration of tumour with pleural or pericardial nodules or malignant pleural. — **Fig. 283**

Schematic illustration of pericardial effusion. — **Fig. 284**

Schematic illustration of Single extrathoracic metastasis in a single organ. — **Fig. 285**

Schematic illustration of Multiple extrathoracic metastases in a single or multiple organ. — **Fig. 287**

Notes

¹ The uncommon superficial spreading 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 T1a.

² T2 tumours with these features are classified T2a if 4 cm or less, or if size cannot be determined, and T2b if greater than 4 cm but not larger than 5 cm.

³ Most pleural (pericardial) effusions with lung cancer are due to tumour. In a few patients, however, multiple microscopical examinations of pleural (pericardial) fluid are negative for tumour, and the fluid is non‐bloody and is not an exudate. Where these elements and clinical judgement dictate that the effusion is not related to the tumour, the effusion should be excluded as a staging element.

pTNM Pathological Classification

The pT and pN categories correspond to the T and N categories.

pM1	Distant metastasis microscopically confirmed

Note

pM0 and pMX are not valid categories.

pN0

Histological examination of hilar and mediastinal lymphadenectomy specimen(s) will ordinarily include 6 or more lymph nodes/stations. Three of these nodes/stations should be mediastinal, including the subcarinal nodes, and three from N1 nodes/stations. Labelling according to the IASLC chart and table of definitions given in the TNM Supplement is desirable. If all the lymph nodes examined are negative, but the number ordinarily examined is not met, classify as pN0.