Table 1.
TNM classification for breast cancer
| pT | Tumor size | ||
|---|---|---|---|
| Tis | In situ | ||
| T1a (cm) | ≤0.5 | ||
| T1b (cm) | 0.5–1 | ||
| T1c (cm) | 1–2 | ||
| T2 (cm) | 2–5 | ||
| T3 (cm) | >5 | ||
| T4a | Extension to chest wall (does not include pectoralis muscle invasion) | ||
| T4b | Ulceration, ipsilateral satellite skin nodules, skin edema | ||
| T4c | a+b | ||
| T4d | Inflammatory cancer | ||
| pN | Lymph node | ||
| N0 | No lymph node metastasis | ||
| N1a | 1–3 axillary nodes | ||
| N1b | Internal mammary nodes with metastasis by sentinel node biopsy but not clinically detected | ||
| N1c | a+b | ||
| N2a | 4–9 axillary nodes | ||
| N2b | Internal mammary nodes, clinically detected, without axillary nodes | ||
| N3a | >10 axillary nodes or infraclavicular | ||
| N3b | Internal mammary nodes, clinically detected, with axillary nodes or >3 axillary nodes and internal axillary mammary nodes with microscopic metastasis by sentinel node biopsy but not clinically detected | ||
| N3c | Supraclavicular | ||
| M | Metastasis | ||
| M0 | No distant metastasis | ||
| Ml | Distant metastasis | ||
| Stage | T | N | M |
| Breast cancer staging | |||
| 0 | Tis | N0 | M0 |
| IA | T1 | N0 | M0 |
| IB | T0/T1 | N1 micro | M0 |
| IIA | T0/T1 | N1 | M0 |
| T2 | N0 | M0 | |
| IIB | T2 | N1 | M0 |
| T3 | N0 | M0 | |
| IIIA | T0/T1/T2 | N2 | M0 |
| T3 | N1/N2 | M0 | |
| IIIB | T4 | N0/N1/N2 | M0 |
| IIIC | Any T | N3 | M0 |
| IV | Any T | Any N | Ml |
Abbreviations: pT, tumor size; TNM, tumor, node, metastasis.