Per the AJCC Cancer Staging Manual, 8th edition, separate tumor nodules in different ipsilateral lobes are classified as T4. Separate tumor nodules are T3 if within the same lobe and M1a if within the contralateral lung.
The updated AJCC 8th edition staging system includes changes from the 7th edition. T classification has the most significant changes:
- A new category of T1mi has been added.
- T1 tumors are now subdivided as T1a, T1b, and T1c if ≤1cm, ≤2cm, or ≤3cm, respectively.
- T2 tumors are 3-5 cm
- T2 now includes any mainstem bronchus invasion (previously if <2cm from the carina it was T3)
- T2 now includes any atelectasis/obstructive pneumonitis extending to the hilum involving part or all of the lung (previously all of the lung was classified as T3)
- T3 tumors are now 5-7cm.
- Tumors >7cm are now classified as T4 (previously T3)
- Tumors invading the diaphragm are now classified as T4 (previously T3)
- Invasion of the mediastinal pleura is no longer used as a T descriptor.
Nodal classification is unchanged. Metastasis now includes "M1b" which is a single extrathoracic metastasis in a single organ (including involvement of a single nonregional node).
Stage groups now include IA1, IA2, and IA3 based on T1a, T1b, and T1c, respectively. Stage IIIC is a new group that includes T3-4 N3 disease. Other N2 and N3 tumors now span stage groups IIIA and IIIB based on T1-2 or T3-4 classification.
For reference:
Primary Tumor
- TX: primary tumor cannot be assessed, or tumor proven by the presence of malignant cells in sputum or bronchial washings but not visualized by imaging or bronchoscopy
- T0: No evidence of primary tumor
- Tis: Carcinoma in situ (squamous cell = SCIS; adenocarcinoma = AIS with pure lepidic pattern, ≤3cm in greatest dimension)
- T1: tumor ≤3 cm, surrounded by lung or visceral pleura, not invading into a main bronchus
- T1mi: minimally invasive adenocarcinoma ≤3cm in greatest dimension with predominantly lepidic pattern and ≤5mm invasion in greatest dimension
- T1a: ≤ 2 cm
- T1b: > 2 cm but ≤ 2 cm
- T1c: >2 but ≤3 cm
- T2: tumor >3 cm but ≤5 cm; or tumor with any of the following: involves main bronchus regardless of distance to the carina; invades visceral pleura (PL1 or PL2); associated with atelectasis or obstructive pneumonitis that extends to the hilar region, involving part or all of the lung
- T2a: >3 cm but ≤4cm (also includes T2 tumors based on proximity to mainstem bronchus, visceral pleural invasion, or atelectasis/obstructive pneumonitis that are <3 cm). Tumors invading directly across a fissure measuring ≤4cm.
- T2b: >4 cm but ≤5cm
- T3: tumor >5 cm but ≤7cm; or tumor that directly invades one of the following: parietal pleura (PL3), chest wall (including superior sulcus tumors), phrenic nerve, parietal pericardium; or separate tumor nodules in the same lobe
- T4: tumor invades: diaphragm, mediastinum, heart, great vessels, trachea, recurrent laryngeal nerve, esophagus, vertebral body, or carina; separate tumor nodule(s) in a different ipsilateral lobe
Regional Lymph Nodes
- N0: no nodes
- N1: ipsilateral peribronchial and/or ipsilateral hilar lymph nodes or intrapulmonary nodes
- N2: ipsilateral mediastinal and/or subcarinal nodes
- N3: contralateral mediastinal, contralateral hilar, ipsilateral or contralateral scalene or supraclavicular nodes
Distant Metastasis
- M0: no distant metastasis
- M1: distant metastasis
- M1a: separate tumor nodule(s) in a contralateral lobe; tumor with pleural or pericardial nodules or malignant pleural or pericardial effusion
- M1b: single extrathoracic metastasis in a single organ (including involvement of a single nonregional node)
- M1c: multiple extrathoracic metastases in a single organ or in multiple organs
Stage Grouping
- 0: TisN0
- IA1: Tis or T1a N0
- IA2: T1b N0
- IA3: T1c N0
- IIA - T1(a or b) N1, T2a N1, T2b N0
- IIB - T2b N1, T3 N0
- IIIA - T1-2 N2, T3 N1, T4 N0-1
- IIIB - T1-2 N3, T3-4 N2
- IIIC - T3-4 N3
- IVA - M1a or M1b
- IVB - M1c
Source: AJCC Cancer Staging Manual, 8th edition