Primary tumor (T)*¶ | |||
T category | T description | ||
TX | Primary tumor cannot be assessed | ||
T0 | No evidence of primary tumor | ||
T1 | Tumor encapsulated or extending into the mediastinal fat; may involve the mediastinal pleura | ||
T1a | Tumor with no mediastinal pleura involvement | ||
T1b | Tumor with direct invasion of mediastinal pleura | ||
T2 | Tumor with direct invasion of the pericardium (either partial or full thickness) | ||
T3 | Tumor with direct invasion into any of the following: Lung, brachiocephalic vein, superior vena cava, phrenic nerve, chest wall, or extrapericardial pulmonary artery or veins | ||
T4 | Tumor with invasion into any of the following: Aorta (ascending, arch, or descending), arch vessels, intrapericardial pulmonary artery, myocardium, trachea, esophagus | ||
* Involvement must be microscopically confirmed in pathological staging, if possible. ¶ T categories are defined by "levels" of invasion; they reflect the highest degree of invasion regardless of how many other (lower-level) structures are invaded. T1, level 1 structures: thymus, anterior mediastinal fat, mediastinal pleura; T2, level 2 structures: pericardium; T3, level 3 structures: lung, brachiocephalic vein, superior vena cava, phrenic nerve, chest wall, hilar pulmonary vessels; T4, level 4 structures: aorta (ascending, arch, or descending), arch vessels, intrapericardial pulmonary artery, myocardium, trachea, esophagus. | |||
Regional lymph nodes (N)Δ | |||
N category | N description | ||
NX | Regional lymph nodes cannot be assessed | ||
N0 | No regional lymph node metastasis | ||
N1 | Metastasis in anterior (perithymic) lymph nodes | ||
N2 | Metastasis in deep intrathoracic or cervical lymph nodes | ||
Δ Involvement must be microscopically confirmed in pathological staging, if possible. | |||
Distant metastasis (M) | |||
M category | M description | ||
M0 | No pleural, pericardial, or distant metastasis | ||
M1 | Pleural, pericardial, or distant metastasis | ||
M1a | Separate pleural or pericardial nodule(s) | ||
M1b | Pulmonary intraparenchymal nodule or distant organ metastasis | ||
Prognostic stage groups | |||
The T, N, and M categories are organized into stage groups, as shown in the table. This schema was developed based primarily on outcomes; in the lower stages, recurrence rates in patients with complete resections were judged most relevant, whereas in higher stages, survival in all patients, regardless of resection status, was weighed more heavily. Practical applicability and clinical implications also were considered. Differences among the stage groups were subjected to statistical analysis and generally were found to have a stepwise progression toward worse survival in multiple patient cohorts (eg, R0, R-any◊). | |||
When T is... | And N is... | And M is... | Then the stage group is... |
T1a,b | N0 | M0 | I |
T2 | N0 | M0 | II |
T3 | N0 | M0 | IIIA |
T4 | N0 | M0 | IIIB |
Any T | N1 | M0 | IVA |
Any T | N0, N1 | M1a | IVA |
Any T | N2 | M0, M1a | IVB |
Any T | Any N | M1b | IVB |
◊ R0: no residual tumor; R-any: any type of resection (no residual tumor, microscopic residual tumor, or macroscopic residual tumor at the primary cancer site or regional nodal sites). |
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