title: Proposal of a new stage grouping of gastric cancer for TNM classification: International Gastric Cancer Association staging project.
abstract: BACKGROUND
  The current AJCC staging system for gastric cancer (AJCC7) incorporated several major revisions to the previous edition. The T and N categories and the stage groups were newly defined, and adenocarcinoma of the esophagogastric junction (EGJ) was reclassified and staged according to the esophageal system. Studies to validate these changes showed inconsistent results. The International Gastric Cancer Association (IGCA) launched a project to support evidence-based revisions to the next edition of the AJCC staging system.
  
  
  METHODS
  Clinical and pathological data on patients who underwent curative gastrectomy at 59 institutions in 15 countries between 2000 and 2004 were retrospectively collected. Patients lost to follow-up within 5 years of surgery were excluded. Patients treated with neoadjuvant therapy were excluded. The data were analyzed in total, and separately by region of treatment.
  
  
  RESULTS
  Of 25,411 eligible cases, 84.8 % were submitted from 24 institutions of Japan and Korea, 6.4 % from other Asian countries, and 8.8 % from 29 Western institutions. The T and N categories of AJCC7 clearly stratified the patient survival. Patients with pN3a and pN3b showed distinct prognosis in all regions, and by introducing pN3a and pN3b into a cluster analysis, we established a new stage grouping with better stratification than AJCC7, especially among stage III subgroups. Survival of Siewert type 2 and 3 EGJ tumors was better stratified by this IGCA stage grouping than by either esophageal or gastric scheme of AJCC7.
  
  
  CONCLUSIONS
  For the next revision of AJCC classification, we propose a new stage grouping based on a large, worldwide data collection.
authors.affiliation: Department of Surgery, Cancer Institute Hospital of Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koto-ku, Tokyo, 135-8550, Japan. takeshi.sano@jfcr.or.jp.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Sano
authors.affiliation: Department of Surgery, Memorial Sloan-Kettering Cancer Center, New York, USA.
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Coit
authors.affiliation: Department of Surgery, Seoul National University Bundang Hospital, Seongnam, Korea.
authors.forename: Hyung Ho
authors.initials: HH
authors.lastname: Kim
authors.affiliation: Department of General Surgery and Surgical Oncology, University of Siena, Siena, Italy.
authors.forename: Franco
authors.initials: F
authors.lastname: Roviello
authors.affiliation: Department of Surgery, Santa Casa Medical School, Sao Paulo, Brazil.
authors.forename: Paulo
authors.initials: P
authors.lastname: Kassab
authors.affiliation: Department of Pathology, Leipzig University, Leipzig, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Wittekind
authors.affiliation: Division of Biostatistics, Japan Clinical Research Support Unit, Tokyo, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Yamamoto
authors.affiliation: Division of Biostatistics, Japan Clinical Research Support Unit, Tokyo, Japan.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Ohashi
mesh_terms: D000230:Adenocarcinoma / Q000145:classification* / Q000556:secondary* / Q000601:surgery; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005500:Follow-Up Studies; D005743:Gastrectomy; D006801:Humans; D007390:International Agencies; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging / Q000592:standards*; D011379:Prognosis; D012189:Retrospective Studies; D013274:Stomach Neoplasms / Q000145:classification* / Q000473:pathology* / Q000601:surgery; D015996:Survival Rate; D055815:Young Adult
keywords: AJCC; Gastric cancer; Stage grouping; TNM classifications; UICC