| Primary tumour size (T) | |
| Tx | No available information |
| T0 | No evidence of primary tumour |
| Tis | Only carcinoma in situ |
| T1 | Maximum diameter 2 cm |
| T2 | Maximum diameter of 4 cm |
| T3 | Maximum diameter over 4 cm |
| T4 | Massive tumour greater than 4 cm diameter, with involvement of adjacent anatomical structures |
| Regional lymph node involvement (N) | |
| Nx | Nodes could not be or were not assessed |
| N0 | No clinically positive nodes |
| N1 | Single ipsilateral node less than 3 cm in diameter |
| N2a | Single ipsilateral nodes 3–6 cm |
| N2b | Multiple ipsilateral nodes less than 6 cm |
| N2c | Bilateral or contralateral nodes less than 6 cm |
| N3 | Any node greater than 6 cm |
| Involvement by distant metastases (M) | |
| Mx | Distant metastasis was not assessed |
| M0 | No evidence of distant metastasis |
| M1 | Distant metastasis is present |