title: Predictive value of the pretreatment extent of disease system in hepatoblastoma: results from the International Society of Pediatric Oncology Liver Tumor Study Group SIOPEL-1 study.
abstract: OBJECTIVE
  Preoperative staging (pretreatment extent of disease [PRETEXT]) was developed for the first prospective liver tumor study by the International Society of Pediatric Oncology (SIOPEL-1 study; preoperative chemotherapy and delayed surgery). Study aims were to analyze the accuracy and interobserver agreement of PRETEXT and to compare the predictive impact of three currently used staging systems.
  
  
  METHODS
  Hepatoblastoma (HB) patients younger than 16 years who underwent surgical resection (128 of 154 patients) were analyzed. The centrally reviewed preoperative staging was compared with postoperative pathology (accuracy) in 91 patients (81%), and the local center staging was compared with the central review (interobserver agreement) in 97 patients (86%), using the agreement beyond change method (weighted kappa). The predictive values of the three staging systems were compared in 110 patients (97%) using survival curves and Cox proportional hazard ratio estimates.
  
  
  RESULTS
  Preoperative PRETEXT staging compared with pathology was correct in 51%, overstaged in 37%, and understaged in 12% of patients (weighted kappa = 0.44; 95% CI, 0.26 to 0.62). The weighted kappa value of the interobserver agreement was 0.76 (95% CI, 0.64 to 0.88). The Children's Cancer Study Group/Pediatric Oncology Group-based staging system showed no predictive value for survival (P = .516), but the tumor-node-metastasis-based system and PRETEXT system showed good predictive values (P = .0021 and P = .0006, respectively). PRETEXT seemed to be superior in the statistical fit.
  
  
  CONCLUSIONS
  PRETEXT has moderate accuracy with a tendency to overstage patients, shows good interobserver agreement (reproducibility), shows superior predictive value for survival, offers the opportunity to monitor the effect of preoperative therapy, and can also be applied in patients who have not had operations. For comparability reasons, we recommend that all HB patients included in trials also be staged according to PRETEXT.
authors.affiliation: Pediatric Surgical Center of Amsterdam, Emma Children's Hospital AMC, PO Box 22700, 1100 DE Amsterdam, the Netherlands. d.c.aronson@amc.uva.nl
authors.forename: Daniël C
authors.initials: DC
authors.lastname: Aronson
authors.forename: J Marco
authors.initials: JM
authors.lastname: Schnater
authors.forename: Chris R
authors.initials: CR
authors.lastname: Staalman
authors.forename: Gerrit J
authors.initials: GJ
authors.lastname: Weverling
authors.forename: Jack
authors.initials: J
authors.lastname: Plaschkes
authors.forename: Giorgio
authors.initials: G
authors.lastname: Perilongo
authors.forename: Julia
authors.initials: J
authors.lastname: Brown
authors.forename: Angela
authors.initials: A
authors.lastname: Phillips
authors.forename: Jean-Bernard
authors.initials: JB
authors.lastname: Otte
authors.forename: Piotr
authors.initials: P
authors.lastname: Czauderna
authors.forename: Gordon
authors.initials: G
authors.lastname: MacKinlay
authors.forename: Anton
authors.initials: A
authors.lastname: Vos
mesh_terms: D002648:Child; D002675:Child, Preschool; D005260:Female; D018197:Hepatoblastoma / Q000473:pathology*; D006801:Humans; D007223:Infant; D038801:International Classification of Diseases; D008113:Liver Neoplasms / Q000473:pathology*; D008297:Male; D009367:Neoplasm Staging / Q000379:methods*; D015588:Observer Variation; D011237:Predictive Value of Tests; D011379:Prognosis; D016016:Proportional Hazards Models; D011446:Prospective Studies