2002 American Joint Committee on Cancer (AJCC) TNM Staging System for the Esophagus Cancer

TX Primary tumor cannot be assessed
T0 No evidence of primary tumor
Tis Carcinoma in situ
T1 Tumor invades lamina propria or submucosa
T2 Tumor invades muscularis propria
T3 Tumor invades adventitia
T4 Tumor invades adjacent structures

NX Regional lymph nodes cannot be assessed
N0 No regional lymph node metastasis
N1 Regional lymph node metastasis

MX: Distant metastasis cannot be assessed
M0: No distant metastasis
M1: Distant metastasis

Tumors of the lower thoracic esophagus:
  M1a Metastasis in celiac lymph nodes
  M1b Other distant metastasis

Tumors of the midthoracic esophagus:
M1a Not applicable
M1b Nonregional lymph nodes and/or other distant

Tumors of the upper thoracic esophagus:
M1a Metastasis in cervical nodes
M1b Other distant metastasis

Stage 0 Tis N0 M0
Stage I T1 N0 M0
Stage IIA T2 N0 M0, T3 N0 M0
Stage IIB T1 N1 M0, T2 N1 M0
Stage III T3 N1 M0, T4 Any N M0
Stage IV Any T Any N M1
Stage IVA Any T Any N M1a
Stage IVB Any T Any N M1b