Prognostic Impact of Tumor Growth Type on 7th AJCC Staging System for Intrahepatic Cholangiocarcinoma: a Single-Center Experience of 659 Cases

Because noticeable changes were made to the 7th American Joint Committee on Cancer (AJCC) tumor-node-metastasis (TNM) staging for intrahepatic cholangiocarcinoma (IHCC), we validated the prognostic impact of tumor staging after macroscopic curative resection of IHCC. A cohort of 659 IHCC patients who underwent R0 (n = 539) or R1 (n = 120) resection were selected with exclusion of R2 resection (n = 111). Study patients were followed up for a parts per thousand yen24 months or until death with no patient lost during survival analysis. Anatomical resection was performed in 599 (90.9 %) and concurrent bile duct resection was conducted in 97 (14.7 %). Median survival periods following R0, R1, and R2 resections were 28, 12, and 3 months, respectively (p = 0.000). In the R0 resection group, the 1-, 3-, 5-, and 10-year tumor recurrence rates were 36.4 %, 57.9 %, 64.7 %, and 65.0 %, respectively, and the 1-, 3-, 5-, and 10-year patient survival rates were 73.1 %, 44.2 %, 33.0 %, and 23.1 %, respectively. Independent risk factors for tumor recurrence and patient survival were tumor growth type, tumor size > 5 cm, perineural invasion, and lymph node metastasis. According to the 7th AJCC staging system, the prognostic contrast was marginal in stage T2-4 tumors without lymph node metastasis (p > 0.8). With our redefined staging system with tumor growth types and risk factors including tumor number and perineural/lymphovascular invasion, clear prognostic contrast was achieved among T1-3 stages (p = 0.000). Growth type of IHCC seems to be essential for determining tumor stage. Although the stratification of the 7th AJCC IHCC staging system seems reasonably established, refinements and further validation could improve prognostic predictability.