title: Evidence for an age cutoff greater than 365 days for neuroblastoma risk group stratification in the Children's Oncology Group.
abstract: OBJECTIVE
  In the Children's Oncology Group, risk group assignment for neuroblastoma is critical for therapeutic decisions, and patients are stratified by International Neuroblastoma Staging System stage, MYCN status, ploidy, Shimada histopathology, and diagnosis age. Age less than 365 days has been associated with favorable outcome, but recent studies suggest that older age cutoff may improve prognostic precision.
  
  
  METHODS
  To identify the optimal age cutoff, we retrospectively analyzed data from the Pediatric Oncology Group biology study 9047 and Children's Cancer Group studies 321p1-p4, 3881, 3891, and B973 on 3,666 patients (1986 to 2001) with documented ages and follow-up data. Twenty-seven separate analyses, one for each different age cutoff (adjusting for MYCN and stage), tested age influence on outcome. The cutoff that maximized outcome difference between younger and older patients was selected.
  
  
  RESULTS
  Thirty-seven percent of patients were younger than 365 days, and 64% were > or = 365 days old (4-year event-free survival [EFS] rate +/- SE: 83% +/- 1% [n = 1,339] and 45% +/- 1% [n = 2,327], respectively; P < .0001). Graphical analyses revealed the continuous nature of the prognostic contribution of age to outcome. The optimal 460-day cutoff we selected maximized the outcome difference between younger and older patients. Forty-three percent were younger than 460 days, and 57% were > or = 460 days old (4-year EFS rate +/- SE: 82% +/- 1% [n = 1,589] and 42% +/- 1% [n = 2,077], respectively; P < .0001). Using a 460-day cutoff (assuming stage 4, MYCN-amplified patients remain high-risk), 5% of patients (365 to 460 days: 4-year EFS 92% +/- 3%; n = 135) fell into a lower risk group.
  
  
  CONCLUSIONS
  The prognostic contribution of age to outcome is continuous in nature. Within clinically relevant risk stratification, statistical support exists for an age cutoff of 460 days.
authors.affiliation: Department of Statistics, University of Florida and Children's Oncology Group, Gainsville, FL 32601, USA. wendy@cog.ufl.edu
authors.forename: W B
authors.initials: WB
authors.lastname: London
authors.forename: R P
authors.initials: RP
authors.lastname: Castleberry
authors.forename: K K
authors.initials: KK
authors.lastname: Matthay
authors.forename: A T
authors.initials: AT
authors.lastname: Look
authors.forename: R C
authors.initials: RC
authors.lastname: Seeger
authors.forename: H
authors.initials: H
authors.lastname: Shimada
authors.forename: P
authors.initials: P
authors.lastname: Thorner
authors.forename: G
authors.initials: G
authors.lastname: Brodeur
authors.forename: J M
authors.initials: JM
authors.lastname: Maris
authors.forename: C P
authors.initials: CP
authors.lastname: Reynolds
authors.forename: S L
authors.initials: SL
authors.lastname: Cohn
mesh_terms: D000367:Age Factors; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D001707:Biopsy, Needle; D002675:Child, Preschool; D015331:Cohort Studies; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007223:Infant; D008297:Male; D009367:Neoplasm Staging; D009447:Neuroblastoma / Q000188:drug therapy / Q000401:mortality* / Q000473:pathology*; D011336:Probability; D011379:Prognosis; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012307:Risk Factors; D016019:Survival Analysis; D013997:Time Factors; D016896:Treatment Outcome; D014481:United States