title: Proposal of a new staging system for intrahepatic cholangiocarcinoma: Analysis of surgical patients from a nationwide survey of the Liver Cancer Study Group of Japan.
abstract: BACKGROUND
  In the current American Joint Committee on Cancer/International Union Against Cancer staging system (seventh edition) for intrahepatic cholangiocarcinoma (ICC), tumor size was excluded, and periductal invasion was added as a new tumor classification-defining factor. The objective of the current report was to propose a new staging system for ICC that would be better for stratifying the survival of patients based on data from the nationwide Liver Cancer Study Group of Japan database.
  
  
  METHODS
  Of 756 patients who underwent surgical resection for ICC between 2000 and 2005, multivariate analyses of the clinicopathologic factors of 419 patients who had complete data sets were performed to elucidate relevant factors for inclusion in a new tumor classification and staging system.
  
  
  RESULTS
  Overall survival data were best stratified using a cutoff value of 2 cm using a minimal P value approach to discriminate patient survival. The 5-year survival rate of 15 patients who had ICC measuring ≤ 2 cm in greatest dimension without lymph node metastasis or vascular invasion was 100%, and this cohort was defined as T1. Multivariate analysis of prognostic factors for 267 patients with lymph node-negative and metastasis-negative (N0M0) disease indicated that the number of tumors, the presence arterial invasion, and the presence major biliary invasion were independent and significant prognostic factors. The proposed new system, which included tumor number, tumor size, arterial invasion, and major biliary invasion for tumor classification, provided good stratification of overall patient survival according to disease stage. Macroscopic periductal invasion was associated with major biliary invasion and an inferior prognosis.
  
  
  CONCLUSIONS
  The proposed new staging system, which includes a tumor cutoff size of 2 cm and major biliary invasion, may be useful for assigning patients to surgery.
authors.affiliation: Hepato-Biliary-Pancreatic Surgery and Artificial Organ and Transplantation Divisions, Department of Surgery, The Tokyo University Hospital, Tokyo, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Sakamoto
authors.affiliation: Hepato-Biliary-Pancreatic Surgery and Artificial Organ and Transplantation Divisions, Department of Surgery, The Tokyo University Hospital, Tokyo, Japan.
authors.forename: Norihiro
authors.initials: N
authors.lastname: Kokudo
authors.affiliation: Department of Biostatistics, School of Public Health, The University of Tokyo, Tokyo, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Matsuyama
authors.affiliation: Department of Pathology, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Michiie
authors.initials: M
authors.lastname: Sakamoto
authors.affiliation: Department of Gastroenterology, Musashino Red Cross Hospital, Tokyo, Japan.
authors.forename: Namiki
authors.initials: N
authors.lastname: Izumi
authors.affiliation: Department of Radiology, Shinshu University School of Medicine, Matsumoto, Japan.
authors.forename: Masumi
authors.initials: M
authors.lastname: Kadoya
authors.affiliation: Department of Gastroenterology, Kanazawa University Hospital, Kanazawa, Japan.
authors.forename: Shuichi
authors.initials: S
authors.lastname: Kaneko
authors.affiliation: Division of Hepato-Biliary-Pancreatic Surgery, Department of Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.
authors.forename: Yonson
authors.initials: Y
authors.lastname: Ku
authors.affiliation: Department of Gastroenterology and Hepatology, Kinki University School of Medicine, Osaka, Japan.
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Kudo
authors.affiliation: Department of Digestive Surgery, Nihon University School of Medicine, Tokyo, Japan.
authors.forename: Tadatoshi
authors.initials: T
authors.lastname: Takayama
authors.affiliation: Department of Clinical Laboratory Medicine, Kurume University Hospital, Kurume, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Nakashima
mesh_terms: D001650:Bile Duct Neoplasms / Q000453:epidemiology / Q000473:pathology*; D018281:Cholangiocarcinoma / Q000453:epidemiology / Q000473:pathology*; D015331:Cohort Studies; D006801:Humans; D007564:Japan / Q000453:epidemiology; D015999:Multivariate Analysis; D009367:Neoplasm Staging / Q000379:methods*; D011379:Prognosis; D011795:Surveys and Questionnaires; D015996:Survival Rate
keywords: biliary invasion; intrahepatic cholangiocarcinoma; periductal invasion; staging system; tumor size