Summary of American Joint Committee on Cancer Staging System for Breast Cancer
| Category | Definition |
|---|---|
| Tumor (T) | |
| T0 | No primary tumor found |
| Tis | Carcinoma in situ |
| T1 | Invasive cancer < 2 cm in greatest dimension |
| T1mic | Microinvasion ≤ 0.1 cm in greatest dimension |
| T1a | Tumor > 0.1 cm but ≤ 0.5 cm in greatest dimension |
| T1b | Tumor > 0.5cm but ≤ 1 cm in greatest dimension |
| T1c | Tumor > 1 cm but ≤ 2 cm in greatest dimension |
| T2 | Tumor > 2 cm but ≤ 5 cm in greatest dimension |
| T3 | Tumor > 5 cm in greatest dimension |
| T4 | Tumor of any size with direct extension to chest wall or skin |
| Regional lymph nodes (N)* | |
| N0 | No regional nodal metastases |
| N1 | Metastasis in mobile ipsilateral axillary nodes |
| N2 | Metastasis to fixed ipsilateral axillary nodes (N2a) or ipsilateral IM nodes in absence of ipsilateral axillary lymph node metastasis (N2b) |
| N3 | Metastases in ipsilateral infraclavicular nodes and axillary nodes (N3a) or ipsilateral IM nodes and axillary nodes (N3b) or metastases to ipsilateral supraclavicular nodes (N3c) |
| Distant metastases (M) | |
| M0 | No distant metastases |
| M1 | Distant metastases |
↵* This system is for clinical staging. Pathologic staging for nodal metastases is further classified for sentinel lymph nodes for detection based on immunohistochemical and molecular assays.
Table is adapted from Singletary and Connolly (14).