title: Validation and Modification of the Japanese Classification System for Liver Metastases from Colorectal Cancer: A Multi-institutional Study.
abstract: BACKGROUND
  A Japanese multicenter study disclosed four prognostic indicators of colorectal cancer liver metastases: ≥5 hepatic tumors (HT), HT size > 5 cm, nodal status (N2) of primary cancer, and the presence of extrahepatic metastases (EM). The Japanese classification was then defined as Stage A, HT1 (≤4 lesions and ≤5 cm) and N0/1; Stage B, HT2 (≥5 lesions or >5 cm) and N0/1, or HT1 and N2; and Stage C, HT2 and N2, HT3 (≥5 lesions and >5 cm) with any N, or EM1 (presence of EM) with any HT/N. This study aimed to validate the prognostic reliability in a recent population and to develop a modified staging system that divided Stage C patients.
  
  
  METHODS
  A total of 1185 patients diagnosed with liver metastases between 2007 and 2008 were enrolled in the study. According to the classification, 358, 257, and 570 patients were categorized as Stages A, B, and C, respectively. Stage C was further divided into two groups: Stage C-I, HT3 and N0/1, HT2 and N2, or HT1 and EM1; and Stage C-II, HT3 and N2, or HT2/3 and EM1.
  
  
  RESULTS
  Cumulative overall survival curves for Stages A, B, and C were significantly different between each two stages (p < 0.0001, p < 0.0001). The modified system discriminated patients with a relatively better outcome (Stage C-I) from desperate patients (Stage C-II) (p < 0.0001).
  
  
  CONCLUSIONS
  The Japanese classification system was adequately validated in a recent population, and the modified system is useful in risk stratification of Stage C cases.
authors.affiliation: Department of Surgery, National Defense Medical College, Tokorozawa, Saitama, Japan. eiji-c@zf6.so-net.ne.jp.
authors.forename: Eiji
authors.initials: E
authors.lastname: Shinto
authors.affiliation: Department of Surgery, Tokyo Metropolitan Cancer and Infectious Diseases Center, Komagome Hospital, Tokyo, Japan.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Takahashi
authors.affiliation: Department of Surgery, Tokyo Metropolitan Cancer and Infectious Diseases Center, Komagome Hospital, Tokyo, Japan.
authors.forename: Tatsuro
authors.initials: T
authors.lastname: Yamaguchi
authors.affiliation: Department of Surgery, Teikyo University, Tokyo, Japan.
authors.forename: Yojiro
authors.initials: Y
authors.lastname: Hashiguchi
authors.affiliation: Department of Surgery, Tochigi Cancer Center, Utsunomiya, Japan.
authors.forename: Kenjiro
authors.initials: K
authors.lastname: Kotake
authors.affiliation: Department of Surgery II, Tokyo Women's Medical University, Tokyo, Japan.
authors.forename: Michio
authors.initials: M
authors.lastname: Itabashi
authors.affiliation: Department of Surgery, Tokyo Metropolitan Hiroo Hospital, Tokyo, Japan.
authors.forename: Masamichi
authors.initials: M
authors.lastname: Yasuno
authors.affiliation: Department of Colorectal Surgery, National Cancer Center Hospital, Tokyo, Japan.
authors.forename: Yukihide
authors.initials: Y
authors.lastname: Kanemitsu
authors.affiliation: Department of Surgery, Japanese Red Cross Kanazawa Hospital, Kanazawa, Japan.
authors.forename: Genichi
authors.initials: G
authors.lastname: Nishimura
authors.affiliation: Department of Surgery, Kurume University Faculty of Medicine, Kurume, Japan.
authors.forename: Yoshito
authors.initials: Y
authors.lastname: Akagi
authors.affiliation: Department of Surgery, Yamagata Prefectural Central Hospital, Yamagata, Japan.
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Sato
authors.affiliation: Department of Surgery, Kamiiida Daiichi General Hospital, Nagoya, Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Kato
authors.affiliation: Department of Surgery, Tokyo Metropolitan Cancer and Infectious Diseases Center, Komagome Hospital, Tokyo, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Matsumoto
authors.affiliation: Department of Surgery, National Defense Medical College, Tokorozawa, Saitama, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Hase
authors.affiliation: Department of Surgery, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Sugihara
mesh_terms: D000368:Aged; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D017024:Chemotherapy, Adjuvant; D015179:Colorectal Neoplasms / Q000473:pathology*; D005260:Female; D006498:Hepatectomy; D006801:Humans; D007564:Japan; D008113:Liver Neoplasms / Q000473:pathology* / Q000556:secondary* / Q000628:therapy; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D009367:Neoplasm Staging; D011379:Prognosis; D015996:Survival Rate; D047368:Tumor Burden