title: Nephrogenic rests in Wilms tumors treated with preoperative chemotherapy: The UK SIOP Wilms Tumor 2001 Trial experience.
abstract: BACKGROUND
  Nephrogenic rests (NRs) are abnormally persistent foci of embryonal cells, thought to be the precursor lesion of Wilms tumors (WTs). To date, their presence has not been systematically examined in WTs treated with preoperative chemotherapy.
  
  
  METHODS
  A systematic analysis of the data on NRs in WTs treated with preoperative chemotherapy obtained from the UK cohort of the International Society of Pediatric Oncology (SIOP) WT 2001 Trial. The study was based on central pathology review of full sets of slides from pathological specimens, with a median of 28 slides reviewed per case.
  
  
  RESULTS
  NRs were identified in 40% of unilateral WTs, including 25% perilobar nephrogenic rest (PLNR), 9% intralobar nephrogenic rest (ILNR), 5% both PLNR and ILNR, and 1% nephroblastomatosis, and in 93% of cases with bilateral lesions. ILNRs were associated with stromal histology and a younger age at diagnosis and found frequently in patients with congenital anomalies associated with WT1 mutation. PLNRs were found frequently in patients with overgrowth syndromes.
  
  
  CONCLUSIONS
  The prevalence of NRs in WTs after preoperative chemotherapy observed in SIOP UK WT 2001 Trial is similar to the previously published data on NRs not treated with preoperative chemotherapy. Their epidemiology supports at least two pathways to Wilms tumorigenesis.
authors.affiliation: Department of Cellular Pathology, University Hospital of Wales/Cardiff University School of Medicine, Cardiff, United Kingdom.
authors.forename: Gordan M
authors.initials: GM
authors.lastname: Vujanić
authors.affiliation: Molecular Haematology and Cancer Biology Unit, Institute of Child Health, University College London, London, United Kingdom.
authors.forename: John R
authors.initials: JR
authors.lastname: Apps
authors.affiliation: Cancer Research UK Clinical Trials Unit, Sir Robert Aitken Building, School of Cancer Sciences, University of Birmingham, Birmingham, United Kingdom.
authors.forename: Veronica
authors.initials: V
authors.lastname: Moroz
authors.affiliation: Molecular Haematology and Cancer Biology Unit, Institute of Child Health, University College London, London, United Kingdom.
authors.forename: Federica
authors.initials: F
authors.lastname: Ceroni
authors.affiliation: Molecular Haematology and Cancer Biology Unit, Institute of Child Health, University College London, London, United Kingdom.
authors.forename: Richard D
authors.initials: RD
authors.lastname: Williams
authors.affiliation: Department of Histopathology, Great Ormond Street Hospital NHS Foundation Trust, London, United Kingdom.
authors.forename: Neil J
authors.initials: NJ
authors.lastname: Sebire
authors.affiliation: Molecular Haematology and Cancer Biology Unit, Institute of Child Health, University College London, London, United Kingdom.
authors.forename: Kathy
authors.initials: K
authors.lastname: Pritchard-Jones
mesh_terms: D000970:Antineoplastic Agents / Q000627:therapeutic use*; D005500:Follow-Up Studies; D006801:Humans; D007390:International Agencies; D007680:Kidney Neoplasms / Q000188:drug therapy / Q000453:epidemiology / Q000473:pathology*; D009367:Neoplasm Staging; D011300:Preoperative Care; D015995:Prevalence; D011379:Prognosis; D006113:United Kingdom / Q000453:epidemiology; D009396:Wilms Tumor / Q000188:drug therapy / Q000453:epidemiology / Q000473:pathology*
chemical_list: D000970:Antineoplastic Agents
keywords: Wilms tumor; nephrogenic rests; preoperative chemotherapy