Stage IIIB includes: T4, N0, M0. T4: Single tumor or multiple tumors of any size involving a major branch of the portal vein or hepatic vein, or tumor(s) with direct invasion of adjacent organs other than the gallbladder or with perforation of visceral peritoneum. N0: No regional lymph node metastasis. M0: No distant metastasis. (AJCC 8th ed.) [from NCI]