Table 1.

American Joint Committee on Cancer staging for gallbladder cancer¹⁶

Stage	TNM	Depth	Regional lymph node status	Distant metastases
0	Tis	In situ	None	None
Ia	T1aN0M0	<Lamina propria	None	None
Ib	T1bN0M0	<Muscular layer	None	None
II	T2N0M0	<Perimuscular tissue; no extension beyond serosa or into liver	None	None
IIIa	T3N0M0	>Serosa and/or directly invades the liver and/or other adjacent organ or structure	None	None
IIIb	T1-3N1M0	Any	Positive nodes along cystic duct bile, common bile duct, hepatic artery and/or portal vein	None
IVa	T4N0M0	Invades main portal vein, hepatic artery or >2 extrahepatic organs/structures	None	None
	T2N1M0	< Perimuscular tissue; no extension beyond serosa or into liver	Positive nodes along cystic duct bile, common bile duct, hepatic artery and/or portal vein	None
IVb	T1-3N2M0	Any	Positive nodes: peri-aortic, pericaval, superior mesenteric artery and/or coeliac artery lymph nodes	None
	T1-3N1-2 M1	Any	Any	Yes

TNM, tumour–node–metastasis; Tis, tumour in situ.