title: Age distributions, birth weights, nephrogenic rests, and heterogeneity in the pathogenesis of Wilms tumor.
abstract: BACKGROUND
  The National Wilms Tumor Study (NWTS) constitutes a unique resource for study of clinical, pathologic, and epidemiologic features of Wilms tumor (WT).
  
  
  METHODS
  Data from NWTS-3,4,5 were compiled for 7,455 patients with tumors of favorable (FH) or anaplastic (AH) histology. The associations of birth weight (BW) and age-at-onset with gender, intralobar (ILNR), and perilobar (PLNR) nephrogenic rests, tumor focality, congenital malformation syndromes, and tumor histology were analyzed using descriptive statistics and linear regression.
  
  
  RESULTS
  Mean BWs for male and female patients without PLNR were 3.52 and 3.36 kg, respectively, and for those with PLNR were 0.12 kg and 0.15 kg heavier. Mean age was 45 months for males with no rests whose tumors were unifocal and of triphasic favorable histology. ILNR or multifocality decreased the mean age by 18 and 10 months, respectively, whereas female gender, blastemal/FH or AH increased it by 3, 10, and 16 months. Over 90% of multifocal tumors occurred in the presence of demonstrated ILNR or PLNR or both. The apparent bimodality of the age distributions and later mean ages-at-onset for females with both unifocal and multifocal tumors were explained in part by the relative deficit in females of ILNR versus PLNR-associated tumors.
  
  
  CONCLUSIONS
  These observations support the view that there are multiple pathways to Wilms tumorigenesis. They will facilitate selection of informative subgroups of patients for molecular analysis that may serve to identify the putative pathway for the majority of patients who cannot be classified provisionally on the basis of ILNR or PLNR.
authors.affiliation: Department of Biostatistics, University of Washington, Seattle, Washington 98195-7232, USA. norm@u.washington.edu
authors.forename: Norman E
authors.initials: NE
authors.lastname: Breslow
authors.forename: J Bruce
authors.initials: JB
authors.lastname: Beckwith
authors.forename: Elizabeth J
authors.initials: EJ
authors.lastname: Perlman
authors.forename: Anthony E
authors.initials: AE
authors.lastname: Reeve
mesh_terms: D017677:Age Distribution; D017668:Age of Onset; D001724:Birth Weight; D002675:Child, Preschool; D005260:Female; D018740:Genetic Heterogeneity; D006801:Humans; D007223:Infant; D007680:Kidney Neoplasms / Q000175:diagnosis / Q000235:genetics* / Q000473:pathology*; D008297:Male; D011379:Prognosis; D009396:Wilms Tumor / Q000175:diagnosis / Q000235:genetics* / Q000473:pathology*