Stage IV includes: IVA (T4, N0-1, M0); IVB (Any T, N2, M0); (Any T, Any N, M1). T4: Tumor invades the main portal vein or hepatic artery, or invades two or more extrahepatic organs or structures. N0: No regional lymph node metastasis. N1: Metastases to nodes along the cystic duct, common bile duct, hepatic artery, and/or portal vein. N2: Metastases to periaortic, pericaval, superior mesenteric artery, and/or celiac artery lymph nodes. M0: No distant metastasis. M1: Distant metastasis. (from AJCC 7th Ed.) [from NCI]