title: Non-Rhabdomyosarcoma Soft Tissue Sarcomas in Children: A Surveillance, Epidemiology, and End Results Analysis Validating COG Risk Stratifications.
abstract: OBJECTIVE
  Non-rhabdomyosarcoma soft tissue sarcomas (NRSTS) are a heterogeneous group of sarcomas that encompass over 35 histologies. With an incidence of ∼500 cases per year in the United States in those <20 years of age, NRSTS are rare and therefore difficult to study in pediatric populations. We used the large Surveillance, Epidemiology, and End Results (SEER) database to validate the prognostic ability of the Children's Oncology Group (COG) risk classification system and to define patient, tumor, and treatment characteristics.
  
  
  METHODS
  From SEER data from 1988 to 2007, we identified patients ≤18 years of age with NRSTS. Data for age, sex, year of diagnosis, race, registry, histology, grade, primary size, primary site, stage, radiation therapy, and survival outcomes were analyzed. Patients with nonmetastatic grossly resected low-grade tumors of any size or high-grade tumors ≤5 cm were considered low risk. Cases of nonmetastatic tumors that were high grade, >5 cm, or unresectable were considered intermediate risk. Patients with nodal or distant metastases were considered high risk.
  
  
  RESULTS
  A total of 941 patients met the review criteria. On univariate analysis, black race, malignant peripheral nerve sheath (MPNST) histology, tumors >5 cm, nonextremity primary, lymph node involvement, radiation therapy, and higher risk group were associated with significantly worse overall survival (OS) and cancer-specific survival (CSS). On multivariate analysis, MPNST histology, chemotherapy-resistant histology, and higher risk group were significantly poor prognostic factors for OS and CSS. Compared to low-risk patients, intermediate patients showed poorer OS (hazard ratio [HR]: 6.08, 95% confidence interval [CI]: 3.53-10.47, P<.001) and CSS (HR: 6.27; 95% CI: 3.44-11.43, P<.001), and high-risk patients had the worst OS (HR: 13.35, 95% CI: 8.18-21.76, P<.001) and CSS (HR: 14.65, 95% CI: 8.49-25.28, P<.001).
  
  
  CONCLUSIONS
  The current COG risk group stratification for children with NRSTS has been validated with a large number of children in the SEER database.
authors.affiliation: Department of Radiation Oncology, University of Colorado School of Medicine, Aurora, Colorado. Electronic address: timothy.waxweiler@ucdenver.edu.
authors.forename: Timothy V
authors.initials: TV
authors.lastname: Waxweiler
authors.affiliation: Department of Radiation Oncology, University of Colorado School of Medicine, Aurora, Colorado.
authors.forename: Chad G
authors.initials: CG
authors.lastname: Rusthoven
authors.affiliation: Department of Radiation Oncology, Billings Clinic, Billings, Montana.
authors.forename: Michelle S
authors.initials: MS
authors.lastname: Proper
authors.affiliation: Division of Hematology and Oncology, Department of Pediatrics, University of Colorado Denver School of Medicine, Aurora, Colorado.
authors.forename: Carrye R
authors.initials: CR
authors.lastname: Cost
authors.affiliation: Division of Urology, Department of Surgery, University of Colorado Denver School of Medicine, Aurora, Colorado.
authors.forename: Nicholas G
authors.initials: NG
authors.lastname: Cost
authors.affiliation: Department of Orthopedics, University of Colorado Denver School of Medicine, Aurora, Colorado.
authors.forename: Nathan
authors.initials: N
authors.lastname: Donaldson
authors.affiliation: Division of Hematology and Oncology, Department of Pediatrics, University of Colorado Denver School of Medicine, Aurora, Colorado.
authors.forename: Timothy
authors.initials: T
authors.lastname: Garrington
authors.affiliation: Division of Hematology and Oncology, Department of Pediatrics, University of Colorado Denver School of Medicine, Aurora, Colorado.
authors.forename: Brian S
authors.initials: BS
authors.lastname: Greffe
authors.affiliation: Department of Orthopedics, University of Colorado Denver School of Medicine, Aurora, Colorado.
authors.forename: Travis
authors.initials: T
authors.lastname: Heare
authors.affiliation: Division of Hematology and Oncology, Department of Pediatrics, University of Colorado Denver School of Medicine, Aurora, Colorado.
authors.forename: Margaret E
authors.initials: ME
authors.lastname: Macy
authors.affiliation: Department of Radiation Oncology, University of Colorado School of Medicine, Aurora, Colorado.
authors.forename: Arthur K
authors.initials: AK
authors.lastname: Liu
mesh_terms: D000293:Adolescent; D000704:Analysis of Variance; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D011379:Prognosis; D012189:Retrospective Studies; D018570:Risk Assessment; D018426:SEER Program; D012509:Sarcoma / Q000208:ethnology / Q000401:mortality* / Q000473:pathology* / Q000532:radiotherapy; D014481:United States