Table I. American Joint Committee on Cancer (AJCC) 6th edition staging system ¹².

Stage	TNM classification
Stage IA	T1, N0, M0
Stage IB	T2, N0, M0
Stage IIA	T3, N0, M0
Stage IIB	T1-3, N1, M0
Stage III	T4, N any, M0
Stage IV	T any, N any, M1

Note: T1, tumor invades lamina propria or muscle layer; T2, tumor invades the perimuscular connective tissue, no extension beyond the serosa or into the liver; T3, tumor perforates the serosa (visceral peritoneum) and/or directly invades the liver and/or one other adjacent organ or structure, such as the stomach, duodenum, colon, or pancreas, omentum or extrahepatic bile ducts; T4, tumor invades main portal vein or hepatic artery or invades multiple extrahepatic organs or structures; N0, no regional lymph node metastasis; N1, regional lymph node metastasis; M0, no distant metastasis; M1, distant metastasis.