title: Multifocality in retroperitoneal sarcoma: a prognostic factor critical to surgical decision-making.
abstract: OBJECTIVE
  To evaluate the significance of multifocality on overall survival (OS) in patients with retroperitoneal sarcoma (RPS) and establish a data-derived, prognostically and therapeutically useful definition of sarcomatosis.
  
  
  BACKGROUND
  The incidence, clinical features, and prognostic significance of multifocality in RPS is unknown. No current standardized definition for sarcomatosis is available.
  
  
  METHODS
  We conducted a retrospective analysis of 393 patients with primary or recurrent nonmetastatic RPS treated at a comprehensive cancer center between 1996 and 2006. Baseline and treatment variables were compared in patients with unifocal and multifocal disease. A multivariate model was used to evaluate the association of multifocality and OS and identify additional prognostic factors in patients with multifocal disease.
  
  
  RESULTS
  The median follow-up time for all patients was 69 months; 79 patients (20%) presented with multifocal disease. The 5-year OS rate was less in the multifocal group compared with the unifocal group (31% vs. 60%, respectively; P < 0.0001). After multivariate analysis, multifocality remained an independent predictor of worse OS {hazard ratio (HR) 1.7 (95% confidence interval (CI), 1.2-2.5); P = 0.004}. Additionally, patients with more tumors had significantly worse prognosis (>7 tumors, HR 2.1 (95% CI, 1.1-3.9); P = 0.03), with a 5-year OS rate of 7%.
  
  
  CONCLUSIONS
  Multifocal RPS is associated with worse OS in patients with either primary or recurrent RPS; Patients with >7 tumors had the worst prognosis. This criterion can be used to define sarcomatosis, thereby identifying patients whose survival will ultimately depend on effective systemic therapy.
authors.affiliation: Department of Surgical Oncology, MD Anderson Cancer Center, University of Texas, Houston, TX 77030-4009, USA.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Anaya
authors.forename: Guy
authors.initials: G
authors.lastname: Lahat
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.forename: Yan
authors.initials: Y
authors.lastname: Xing
authors.forename: Janice N
authors.initials: JN
authors.lastname: Cormier
authors.forename: Peter W
authors.initials: PW
authors.lastname: Pisters
authors.forename: Dina C
authors.initials: DC
authors.lastname: Lev
authors.forename: Raphael E
authors.initials: RE
authors.lastname: Pollock
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012186:Retroperitoneal Neoplasms / Q000401:mortality / Q000473:pathology* / Q000601:surgery*; D012189:Retrospective Studies; D012509:Sarcoma / Q000401:mortality / Q000473:pathology* / Q000601:surgery*; D015996:Survival Rate