title: Conditional disease-free survival after surgical resection of gastrointestinal stromal tumors: a multi-institutional analysis of 502 patients.
abstract: OBJECTIVE
  Gastrointestinal stromal tumors (GISTs) are the most commonly diagnosed mesenchymal tumors of the gastrointestinal tract. The risk of recurrence following surgical resection of GISTs is typically reported from the date of surgery. However, disease-free survival (DFS) over time is dynamic and changes based on disease-free time already accumulated following surgery.
  
  
  OBJECTIVE
  To assess the comparative performance of established GIST recurrence risk prognostic scoring systems and to characterize conditional DFS following surgical resection of GISTs.
  
  
  METHODS
  A retrospective cohort study of 502 patients who underwent surgery for a primary, nonmetastatic GIST between January 1, 1998, and December 31, 2012, at 7 major academic cancer centers in the United States and Canada.
  
  
  METHODS
  Disease-free survival of the patients was classified according to 5 prognostic scoring systems, including the National Institutes of Health criteria, modified National Institutes of Health criteria, Memorial Sloan Kettering Cancer Center GIST nomogram, and American Joint Committee on Cancer gastric and nongastric categories. The concordance index (also known as the C statistic or the area under the receiver operating curve) of established GIST recurrence risk prognostic scoring systems. Conditional DFS estimates were calculated.
  
  
  RESULTS
  Overall 1-year, 3-year, and 5-year DFS following resection of GISTs was 95%, 83%, and 74%, respectively. All the prognostic scoring systems had fair prognostic ability. For all tumor sites, the American Joint Committee on Cancer gastric category demonstrated the best discrimination (C = 0.79). Using conditional DFS, the probability of remaining disease free for an additional 3 years given that a patient was disease free at 1 year, 3 years, and 5 years was 82%, 89%, and 92%, respectively. Patients with the highest initial recurrence risk demonstrated the greatest increase in conditional survival as time elapsed.
  
  
  CONCLUSIONS
  Conditional DFS improves over time following resection of GISTs. This is valuable information about long-term prognosis to communicate to patients who are disease free after a period following surgery.
authors: Department of Surgery, The Johns Hopkins University, Baltimore, Maryland.
authors: Danielle A
authors: DA
authors: Bischof
authors: Department of Surgery, The Johns Hopkins University, Baltimore, Maryland.
authors: Yuhree
authors: Y
authors: Kim
authors: Department of Surgery, The Johns Hopkins University, Baltimore, Maryland.
authors: Rebecca
authors: R
authors: Dodson
authors: University Health Network, Toronto, Ontario, Canada3Department of Surgery, University of Toronto, Toronto, Ontario, Canada.
authors: M Carolina
authors: MC
authors: Jimenez
authors: Department of Surgery, University of Toronto, Toronto, Ontario, Canada4Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada.
authors: Ramy
authors: R
authors: Behman
authors: Department of Surgery, Duke University, Durham, North Carolina.
authors: Andrei
authors: A
authors: Cocieru
authors: Department of Surgery, Emory University, Atlanta, Georgia.
authors: Sarah B
authors: SB
authors: Fisher
authors: Department of Surgery, Medical College of Wisconsin, Milwaukee.
authors: Ryan T
authors: RT
authors: Groeschl
authors: Department of Surgery, Emory University, Atlanta, Georgia.
authors: Malcolm H
authors: MH
authors: Squires
authors: Department of Surgery, Emory University, Atlanta, Georgia.
authors: Shishir K
authors: SK
authors: Maithel
authors: Department of Surgery, Duke University, Durham, North Carolina.
authors: Dan G
authors: DG
authors: Blazer
authors: Department of Surgery, Emory University, Atlanta, Georgia.
authors: David A
authors: DA
authors: Kooby
authors: Department of Surgery, Medical College of Wisconsin, Milwaukee.
authors: T Clark
authors: TC
authors: Gamblin
authors: Department of Surgery, University of Virginia, Charlottesville.
authors: Todd W
authors: TW
authors: Bauer
authors: University Health Network, Toronto, Ontario, Canada3Department of Surgery, University of Toronto, Toronto, Ontario, Canada.
authors: Fayez A
authors: FA
authors: Quereshy
authors: Department of Surgery, University of Toronto, Toronto, Ontario, Canada4Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada.
authors: Paul J
authors: PJ
authors: Karanicolas
authors: Department of Surgery, University of Toronto, Toronto, Ontario, Canada4Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada.
authors: Calvin H L
authors: CH
authors: Law
authors: Department of Surgery, The Johns Hopkins University, Baltimore, Maryland.
authors: Timothy M
authors: TM
authors: Pawlik
mesh_terms: D002170:Canada; D018572:Disease-Free Survival; D005260:Female; D046152:Gastrointestinal Stromal Tumors / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D011379:Prognosis; D012189:Retrospective Studies; D012306:Risk; D013274:Stomach Neoplasms / Q000601:surgery*; D016019:Survival Analysis; D016896:Treatment Outcome; D014481:United States