Table 1.

Essentials of T, N, and M descriptors for the lung cancer and individual staging

T descriptors (primary tumor)
Tis	Carcinoma in situ
T1	T1a(mi) – Minimally invasive adenocarcinoma T1a – tumor ≤ 1 cm in greatest dimension T1b – tumor > 1 cm but ≤ 2 cm in greatest dimension T1c – tumor > 2 cm but ≤ 3 cm in greatest dimension
T2	Invasion of visceral pleura T2a – tumor > 3 cm but ≤ 4 cm in greatest dimension T2b – tumor > 4 cm but ≤ 5 cm in greatest dimension
T3	Separate nodule in the same lobe (primary tumor) Invasion of chest wall (including parietal pleura), phrenic nerve, pericardium Tumor > 5 cm but ≤ 7 cm in greatest dimension
T4	Separate nodule in a same side (primary tumor) but a different lobe Invasion of diaphragm, mediastinum, heart, trachea, and esophagus, etc. Tumor > 7 cm in greatest dimension
N descriptors (regional lymph node involvement)
N0	No lymph node metastasis
N1	Metastasis in ipsilateral peribronchial, hilar, or intrapulmonary lymph node(s)
N2	Metastasis in ipsilateral mediastinal or subcarinal lymph node(s)
N3	Metastasis in scalene, supraclavicular, or contralateral mediastinal, hilar lymph node(s)
M descriptors (distant metastasis)
M0	No distant metastasis
M1a	Separate tumor nodule(s) contralateral lobe or pleural/pericardial nodule or malignant pleural/pericardial effusion
M1b	Single extrathoracic metastasis
M1c	Multiple extrathoracic metastasis in one or more organs
Individual staging
Stage 0	TisN0M0
Stage I	T1, T2a with N0M0
Stage II	T2b, T3 with N0M0 T1, T2 with N1M0
Stage III	T4N0M0 T3N1, T4N1 Any T, N2-3M0
Stage IV	Any T, Any N, M1