206 Background: The objective was to clarify the prognostic impact of the 8th edition of American Joint Committee on Cancer (AJCC)/International Union Against Cancer (UICC) of intrahepatic cholangiocarcinoma (ICC). Methods: ICC patients who underwent hepatectomy for ICC between 2002 and 2016 were enrolled. The survival impact of AJCC/UICC 8th edition was examined. Results: A total of 103 resected patients were enrolled. The 5-year disease-specific survival (DSS) rate was 75.9% in T1a (n = 23), 88.9% in T1b (n = 10), 14.9% in T2 (n = 24), 52.5% in T3 (n = 11), and 15.2% in T4 (n = 35). The DSS was comparable among T2, T3, and T4 (p = 0.345, 0.295). The 5-year DSS was 87.5% in stage IA, 88.9% in IB, 18.1% in II, 66.7% in IIIA, and 15.0% in IIIB. The DSS rates of stage II and stage IIIB were comparable, and the DSS rate of stage II was worse than that of stage IIIB. A multivariate analysis identified multiple tumors (hazard ratio [HR]: 2.821), periductal infiltrating (HR: 2.439), perforation of the visceral peritoneum (HR: 1.850), and vascular invasion (HR: 1.872) as independent prognostic factors that were associated with the DSS. Lymph node metastasis (HR: 1.715) was not an independent prognostic factor. The optimum tumor size with the greatest difference in the DSS was 2 cm (p = 0.014). The new T classification was developed as follows: T1, size ≤ 2 cm without other factors; T2, size > 2 cm without other factors; T3, vascular invasion or perforation of the visceral peritoneum; and T4, multiple tumors or periductal infiltrating. The HR of lymph node metastasis was similar to that of the low-HR factors, so lymph node metastasis was categorized as Stage IIIA. The 5-year DSS was 100% in T1 (n = 7), 76.6% in T2 (n = 28), 45.1% in T3 (n = 28), and 3.4% in T4 (n = 40). There were differences in the DSS between T2 and T3 (p = 0.035) and between T3 and T4 (p = 0.003). The 5-year DSS was 100% in stage I, 85.6% in II, 42.4% in IIIA, and 3.4% in IIIB (Fig. 2d). There were significant differences in the DSS between stage II and IIIA (p = 0.013) and between IIIA and IIIB (p = 0.026). Conclusions: T2, T3, and T4 of AJCC/UICC overlapped with regard to the DSS. The new staging can classify ICC patients with sufficient prognostic differences.
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