title: Subgroups of patients with very large gastrointestinal stromal tumors with distinct prognoses: a multicenter study.
abstract: OBJECTIVE
  Any gastrointestinal stromal tumors (GISTs) larger than 10 cm are classified as "high risk" according to the modified National Institutes of Health consensus criteria. We conducted a multicenter study to identify a subgroup with moderate prognosis even within the "high-risk" group.
  
  
  METHODS
  We retrospectively collected data on 107 patients with tumors ≥10 cm from a multicenter database of GIST patients. Patients with macroscopic residual lesions or tumor rupture were excluded. The relationship between recurrence-free survival (RFS) and clinicopathological factors was analyzed.
  
  
  RESULTS
  The median tumor size and mitotic count were 12.5 cm and 8/50 HPF. The RFS rate was 58.5% at 3 years, 52.1% at 5 years. Only mitotic count was an independent prognostic factor of RFS in the multivariate analysis (P = 0.001). The hazard ratio for recurrence in the subgroup with mitotic count >5/50 HPF was 2.91 (95% confidence interval, 1.53 to 5.56). The subgroup with mitotic count ≤5/50 HPF showed significantly better RFS than the mitotic count >5/50 HPF subgroup (P < 0.001).
  
  
  CONCLUSIONS
  Mitotic count is closely associated with outcome in patients with large GISTs. This suggests that the subset of large GISTs with low mitotic counts may be considered as "intermediate-risk" lesions.
authors.affiliation: Department of Gastroenterological Surgery, Osaka University Graduate School of Medicine, Osaka, Japan.
authors.forename: Noriko
authors.initials: N
authors.lastname: Wada
authors.forename: Yukinori
authors.initials: Y
authors.lastname: Kurokawa
authors.forename: Toshirou
authors.initials: T
authors.lastname: Nishida
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Takahashi
authors.forename: Takahiro
authors.initials: T
authors.lastname: Toyokawa
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kusanagi
authors.forename: Seiichi
authors.initials: S
authors.lastname: Hirota
authors.forename: Toshimasa
authors.initials: T
authors.lastname: Tsujinaka
authors.forename: Masaki
authors.initials: M
authors.lastname: Mori
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Doki
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018572:Disease-Free Survival; D005260:Female; D005500:Follow-Up Studies; D005770:Gastrointestinal Neoplasms / Q000401:mortality* / Q000473:pathology*; D046152:Gastrointestinal Stromal Tumors / Q000401:mortality* / Q000473:pathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008940:Mitotic Index; D009364:Neoplasm Recurrence, Local; D011379:Prognosis; D016016:Proportional Hazards Models; D012189:Retrospective Studies
keywords: high risk; large GISTs; mitosis; mitotic count