Health.amTable 18-4. TNM staging system for esophageal cancers.1
| Primary tumor infiltration (T) | |
| TX | Primary tumor cannot be assessed |
| TO | No evidence of primary tumor |
| Tis | Carcinoma in situ |
| T1 | Tumor limited to mucosa/submucosa |
| T2 | Tumor involving muscularis propria |
| T3 | Involvement of adventitia, no extraesophageal structures |
| T4 | Extension into extraesophageal structures |
Regional lymph nodes (N) | |
| NX | Regional lymph nodes cannot be assessed |
| N0 | No nodal involvement |
| N1 | Regional nodes involved |
Distant metastasis (M) | |
| MX | Distant metastases cannot be assessed |
| M0 | No distant metastases |
| M1 | Distant metastases for tumors of the lower thoracic esophagus: |
| M1a | Metastases in celiac nodes |
| M1b | Other distant metastases for tumors of the cervical thoracic esophagus: |
| M1a | Metastases in cervical lymph nodes |
| M1b | Other distant metastases for tumors in the middle thoracic esophagus: |
| M1a | Not applicable |
| M1b | Nonregional lymph nodes or other distant metastases |
| Stage grouping | |
| Stage 0 | Tis | N0 | M0 |
| Stage I | T1 | N0 | M0 |
| Stage IIA | T2-3 | N0 | M0 |
| Stage IIB | T1-2 | N1 | M0 |
| Stage III | T3 | N1 | M0 |
| T4 | Any N | M0 | |
| Stage IV | Any T | Any N | M1 |
| Stage IV A | Any T | Any N | M1a |
| Stage IV B | Any T | Any N | M1b |