Analysis of extrahepatic bile duct carcinomas according to the new American Joint Committee on Cancer staging system focused on tumor classification problems in 222 patients

BACKGROUND. Although the sixth edition of the American Joint Committee on Cancer (AJCC) staging system for extrahepatic bile duct carcinoma was updated, the system has a problem on T classification due to its ambiguous definition of T1 as "tumor confined to bile duct histologically" and T2 as "tumor invading beyond the bile duct." METHODS. The authors considered the outermost part of the muscle layer or fibrous tissue as within the extrahepatic bile duct and considered the area starting from large clusters of adipose tissue as beyond the extrahepatic bile duct. After designing a precise definition of the extrahepatic bile duct wall, (hey analyzed the new AJCC staging system in 222 patients with of extrahepatic bile duct carcinomas. Then, other clinicopathologic variables for prognosis were evaluated using univariate and multivariate analyses. RESULTS. The 5-year survival rates for patients with tumors that were classified as T1, T2, T3, and T4 were 53.1%, 29.7%, 24.9%, and 0%, respectively. There was a significant difference in survival between patients with T1 tumors and T2 tumors (P < 0.05), but not between patients with T2 tumors and T3 tumors. Significant prognostic factors included depth of invasion (P < 0.005), lymph node metastasis (P < 0.005), and patient age (P < 0.05). CONCLUSIONS. Based on a proposed histologic definition, depth of invasion was practical for evaluating the prognosis of patients with middle and upper extrahepatic bile duct carcinomas. Therefore, the authors recommended changing the current pT1 and pT2 classifications to more precise pathologic terminology.