Table.

Tumor, Node, Metastasis Staging Classification (8th Edition)¹²

Primary Tumor
TX	Primary tumor cannot be assessed.
T0	No evidence of primary tumor
Tis	Carcinoma in situ
T1	Tumor invades the lamina propria, muscularis mucosa, or submucosa.
T1a	Tumor invades the lamina propria or muscularis mucosa.
T1b	Tumor invades the submucosa.
T2	Tumor invades the muscularis propria.
T3	Tumor invades the adventitia.
T4	Tumor invades the adjacent structures.
T4a	Tumor invades the pleura, pericardium, azygos vein, diaphragm, or peritoneum.
T4b	Tumor invades the other adjacent structures, such as the aorta, vertebral body, or trachea.
Regional Lymph Nodes
NX	Lymph node status cannot be assessed.
N0	No regional lymph node metastases
N1	Metastasis in ≤2 regional lymph nodes
N2	Metastasis in 3-6 regional lymph nodes
N3	Metastasis in ≥7 regional lymph nodes
Distant Metastases
MX	Presence of distant metastases cannot be assessed.
M0	No distant metastases
M1	Distant metastases