Stage II includes: IIA: (T1, N1, M0); (T2, N0, M0); IIB: (T2, N1, M0); (T3, N0, M0); (T3, N1, M0). T1: Tumor invading the bile duct wall with a depth less than 5 mm. T2: Tumor invading the bile duct wall with a depth of 5-12 mm. T3: Tumor invading the bile duct wall with a depth greater than 12 mm. N0: No regional lymph node metastasis. N1: Metastasis in one to three regional lymph nodes. M0: No distant metastasis. (AJCC 8th ed.) [from NCI]