Table 2.

7^th edition of the American Joint Committee on Cancer’s staging system for small bowel adenocarcinoma

Primary tumor (T)	Regional lymph nodes (N)			Distant metastases (M)
Tx - Primary tumor cannot be assessed	Nx - Regional lymph nodes cannot be assessed			Mx - Distant metastases not assessed
Tis - Carcinoma in situ	N0 - No regional node metastasis			M0 - Distant metastases not present
T1a - Tumor invades lamina propria	N1 - Metastasis in 1-3 regional nodes			M1 - Distant metastases present
T1b - Tumor invades submucosa	N2 - Metastasis in 4 or more regional nodes
T2 - Tumor invades muscularis propria	Stage grouping
T3 - Tumor invades into the subserosa	Stage 0	Tis	N0	M0
	Stage I	T1-T2	N0	M0
T4 - Tumor perforates visceral peritoneum; or invades pancreas/bile duct	Stage IIA	T3	N0	M0
	Stage IIB	T4	N0	M0
	Stage IIIA	Any T	N1	M0
	Stage IIIB	Any T	N2	M0
	Stage IV	Any T	Any N	M1