title: Identification of Discrete Prognostic Groups in Ewing Sarcoma.
abstract: BACKGROUND
  Although multiple prognostic variables have been proposed for Ewing sarcoma (EWS), little work has been done to further categorize these variables into prognostic groups for risk classification.
  
  
  METHODS
  We derived initial prognostic groups from 2,124 patients with EWS in the SEER database. We constructed a multivariable recursive partitioning model of overall survival using the following covariates: age; stage; race/ethnicity; sex; axial primary; pelvic primary; and bone or soft tissue primary. Based on this model, we identified risk groups and estimated 5-year overall survival for each group using Kaplan-Meier methods. We then applied these groups to 1,680 patients enrolled on COG clinical trials.
  
  
  RESULTS
  A multivariable model identified five prognostic groups with significantly different overall survival: (i) localized, age <18 years, non-pelvic primary; (ii) localized, age <18, pelvic primary or localized, age ≥18, white, non-Hispanic; (iii) localized, age ≥18, all races/ethnicities other than white, non-Hispanic; (iv) metastatic, age <18; and (v) metastatic, age ≥18. These five groups were applied to the COG dataset and showed significantly different overall and event-free survival based upon this classification system (P < 0.0001). A sub-analysis of COG patients treated with ifosfamide and etoposide as a component of therapy evaluated these findings in patients receiving contemporary therapy.
  
  
  CONCLUSIONS
  Recursive partitioning analysis yields discrete prognostic groups in EWS that provide valuable information for patients and clinicians in determining an individual patient's risk of death. These groups may enable future clinical trials to adjust EWS treatment according to individualized risk.
authors.affiliation: Department of Pediatrics, University of California, San Francisco School of Medicine, San Francisco, California.
authors.forename: Erin E
authors.initials: EE
authors.lastname: Karski
authors.affiliation: Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: McIlvaine
authors.affiliation: Department of Epidemiology and Biostatistics, University of California, San Francisco, California.
authors.forename: Mark R
authors.initials: MR
authors.lastname: Segal
authors.affiliation: Department of Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California.
authors.forename: Mark
authors.initials: M
authors.lastname: Krailo
authors.affiliation: Dana-Farber/Boston Children's Cancer and Blood Disorders Center, Boston, Massachusetts.
authors.forename: Holcombe E
authors.initials: HE
authors.lastname: Grier
authors.affiliation: Department of Pediatrics, New York University Langone Medical Center, New York City, New York.
authors.forename: Linda
authors.initials: L
authors.lastname: Granowetter
authors.affiliation: Division of Oncology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania.
authors.forename: Richard B
authors.initials: RB
authors.lastname: Womer
authors.affiliation: Department of Pediatrics, Memorial Sloan-Kettering Cancer Center, New York City, New York.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Meyers
authors.affiliation: Department of Pediatrics, Providence Sacred Heart Medical Center and Children's Hospital, Spokane, Washington.
authors.forename: Judy
authors.initials: J
authors.lastname: Felgenhauer
authors.affiliation: Department of Pediatrics, Stanford University School of Medicine, Palo Alto, California.
authors.forename: Neyssa
authors.initials: N
authors.lastname: Marina
authors.affiliation: Department of Pediatrics, University of California, San Francisco School of Medicine, San Francisco, California.
authors.forename: Steven G
authors.initials: SG
authors.lastname: DuBois
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D001859:Bone Neoplasms / Q000145:classification / Q000188:drug therapy / Q000401:mortality*; D002648:Child; D002675:Child, Preschool; D016208:Databases, Factual; D005047:Etoposide / Q000627:therapeutic use; D005260:Female; D006801:Humans; D007069:Ifosfamide / Q000627:therapeutic use; D007223:Infant; D007231:Infant, Newborn; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D018426:SEER Program; D012512:Sarcoma, Ewing / Q000145:classification / Q000188:drug therapy / Q000401:mortality*
chemical_list: D005047:Etoposide; D007069:Ifosfamide
keywords: Ewing sarcoma; prognostic groups; recursive partitioning