title: Outcome after surgery alone or with restricted use of chemotherapy for patients with low-risk neuroblastoma: results of Children's Oncology Group study P9641.
abstract: OBJECTIVE
  The primary objective of Children's Oncology Group study P9641 was to demonstrate that surgery alone would achieve 3-year overall survival (OS) ≥ 95% for patients with asymptomatic International Neuroblastoma Staging System stages 2a and 2b neuroblastoma (NBL). Secondary objectives focused on other low-risk patients with NBL and on those who required chemotherapy according to protocol-defined criteria.
  
  
  METHODS
  Patients underwent maximally safe resection of tumor. Chemotherapy was reserved for patients with, or at risk for, symptomatic disease, with less than 50% tumor resection at diagnosis, or with unresectable progressive disease after surgery alone.
  
  
  RESULTS
  For all 915 eligible patients, 5-year event-free survival (EFS) and OS were 89% ± 1% and 97% ± 1%, respectively. For patients with asymptomatic stage 2a or 2b disease, 5-year EFS and OS were 87% ± 2% and 96% ± 1%, respectively. Among patients with stage 2b disease, EFS and OS were significantly lower for those with unfavorable histology or diploid tumors, and OS was significantly lower for those ≥ 18 months old. For patients with stage 1 and 4s NBL, 5-year OS rates were 99% ± 1% and 91% ± 1%, respectively. Patients who required chemotherapy at diagnosis achieved 5-year OS of 98% ± 1%. Of all patients observed after surgery, 11.1% experienced recurrence or progression of disease.
  
  
  CONCLUSIONS
  Excellent survival rates can be achieved in asymptomatic low-risk patients with stages 2a and 2b NBL after surgery alone. Immediate use of chemotherapy may be restricted to a minority of patients with low-risk NBL. Patients with stage 2b disease who are older or have diploid or unfavorable histology tumors fare less well. Future studies will seek to refine risk classification.
authors.affiliation: University of Calgary and Alberta Children’s Hospital, Calgary, Alberta, Canada. doug.strother@albertahealthservices.ca
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Strother
authors.forename: Wendy B
authors.initials: WB
authors.lastname: London
authors.forename: Mary Lou
authors.initials: ML
authors.lastname: Schmidt
authors.forename: Garrett M
authors.initials: GM
authors.lastname: Brodeur
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Shimada
authors.forename: Paul
authors.initials: P
authors.lastname: Thorner
authors.forename: Margaret H
authors.initials: MH
authors.lastname: Collins
authors.forename: Edward
authors.initials: E
authors.lastname: Tagge
authors.forename: Stanton
authors.initials: S
authors.lastname: Adkins
authors.forename: C Patrick
authors.initials: CP
authors.lastname: Reynolds
authors.forename: Kevin
authors.initials: K
authors.lastname: Murray
authors.forename: Robert S
authors.initials: RS
authors.lastname: Lavey
authors.forename: Katherine K
authors.initials: KK
authors.lastname: Matthay
authors.forename: Robert
authors.initials: R
authors.lastname: Castleberry
authors.forename: John M
authors.initials: JM
authors.lastname: Maris
authors.forename: Susan L
authors.initials: SL
authors.lastname: Cohn
mesh_terms: D000293:Adolescent; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000009:adverse effects / Q000627:therapeutic use*; D017024:Chemotherapy, Adjuvant; D002648:Child; D002675:Child, Preschool; D018450:Disease Progression; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D007223:Infant; D053208:Kaplan-Meier Estimate; D008297:Male; D009367:Neoplasm Staging; D009447:Neuroblastoma / Q000188:drug therapy* / Q000401:mortality / Q000473:pathology / Q000601:surgery*; D018579:Patient Selection; D011446:Prospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome; D014481:United States; D055815:Young Adult