title: Proposal of a new staging system for mass-forming intrahepatic cholangiocarcinoma: a multicenter analysis by the Study Group for Hepatic Surgery of the Japanese Society of Hepato-Biliary-Pancreatic Surgery.
abstract: BACKGROUND
  Recently, the Liver Cancer Study Group of Japan (LCSGJ) staging system for intrahepatic cholangiocarcinoma (ICC) was followed by a proposal of the American Committee on Cancer (AJCC)/International Union Against Cancer (UICC) system. The present study aimed to assess the accuracy of both systems to predict survival after curative resection for mass-forming ICC and to establish a new staging system based on survival analysis results. The present study was conducted as a project study of the Japanese Society of Hepato-Biliary-Pancreatic Surgery.
  
  
  METHODS
  Clinical data from 233 patients who underwent curative resection for mass-forming ICC were retrospectively reviewed. Survival analysis was performed to identify predictors of postoperative outcomes, and a new staging system was established. The survival stratification of our proposed system was compared with two previous staging systems.
  
  
  RESULTS
  A N0M0 cohort analysis demonstrated that tumor size, tumor number, and vascular invasion were independently associated with survival after curative resection for mass-forming ICC, whereas serosal and periductal invasion were not. Of patients with nodal metastases, patients with T4 tumor had significantly lower overall survival rate than patients with T1, T2, or T3 tumor. Thus, we proposed a new staging system as follows: serosal invasion was excluded from the LCSGJ T categories, and patients with nodal metastases were divided into stage IVA or IVB according to T classification. The new system better stratified survival after curative resection for mass-forming ICC than the two previous systems.
  
  
  CONCLUSIONS
  The AJCC/UICC staging system failed to stratify the Japanese patients with mass-forming ICC. The new staging system provided better survival prediction in the patients who underwent curative resection for mass-forming ICC, although further studies are necessary to evaluate the impact of tumor size on survival.
authors: Department of Hepato-Biliary-Pancreatic Surgery, Osaka City University Graduate School of Medicine, Osaka, Japan.
authors: Takahiro
authors: T
authors: Uenishi
authors: Shunichi
authors: S
authors: Ariizumi
authors: Taku
authors: T
authors: Aoki
authors: Tomoki
authors: T
authors: Ebata
authors: Masayuki
authors: M
authors: Ohtsuka
authors: Eiichi
authors: E
authors: Tanaka
authors: Hiroshi
authors: H
authors: Yoshida
authors: Satoru
authors: S
authors: Imura
authors: Masaki
authors: M
authors: Ueno
authors: Norihiro
authors: N
authors: Kokudo
authors: Masato
authors: M
authors: Nagino
authors: Satoshi
authors: S
authors: Hirano
authors: Shoji
authors: S
authors: Kubo
authors: Michiaki
authors: M
authors: Unno
authors: Mitsuo
authors: M
authors: Shimada
authors: Hiroki
authors: H
authors: Yamaue
authors: Masakazu
authors: M
authors: Yamamoto
authors: Masaru
authors: M
authors: Miyazaki
authors: Tadahiro
authors: T
authors: Takada
mesh_terms: D001650:Bile Duct Neoplasms / Q000473:pathology*; D001653:Bile Ducts, Intrahepatic; D018281:Cholangiocarcinoma / Q000473:pathology*; D006801:Humans; D007564:Japan; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D012189:Retrospective Studies; D012955:Societies, Medical; D016896:Treatment Outcome
keywords: Mass-forming intrahepatic cholangiocarcinoma; Postoperative outcomes; Tumor-node-metastasis classification