title: Effects of surgical excision and radiation on medulloblastoma cell invasiveness.
abstract: OBJECTIVE
  Surgical resection and adjuvant radiation are mainstays of medulloblastoma (MB) patient management. We utilized a novel 3-dimensional assay to identify how (a) radiation, (b) excision of the primary tumour aggregate, and (c) both treatments combined influence MB cell invasiveness.
  
  
  METHODS
  Five MB cell lines (UW228-1, 2 and 3; Daoy, and Madsen) were implanted onto a 3-dimensional, type I collagen gel assay to assess tumour invasion distance over five days, in response to (1) needle-assisted excision of the central cell aggregate; (2) pre-exposure to single-dose and fractionated dose irradiation in doses from 6-25 and 8-24 Gy, respectively; and (3) excision plus either single-dose or fractionated radiation.
  
  
  RESULTS
  Within hours, individual MB cells detached from the surface of the cell aggregates and invaded the collagen matrix, to distances up to 1200 microm and at rates up to 300 microm daily. The UW228-1 cell line was less invasive than the other cell lines and was dropped from further analysis. In the four remaining lines, a dose-dependent decline in tumour invasiveness was identified, both for single-dose and fractionated radiation, which achieved statistically decreased invasion distances at higher doses, especially of fractionated irradiation. Excision of the central tumour aggregate tended towards exerting a late effect on cell invasion, but exerted no significant influence on the radio-sensitivity of residual cells.
  
  
  CONCLUSIONS
  Both single-dose and fractionated dose irradiation appear to inhibit MB cell invasiveness in a dose-dependent manner, whereas excision of the central cell aggregate exerts no effect on residual invading cells.
authors.affiliation: Division of Neurosurgery, London Health Sciences Centre, London, Ontario, Canada.
authors.forename: Adrianna
authors.initials: A
authors.lastname: Ranger
authors.forename: Warren
authors.initials: W
authors.lastname: McDonald
authors.forename: Glenn S
authors.initials: GS
authors.lastname: Bauman
authors.forename: Rolando
authors.initials: R
authors.lastname: Del Maestro
mesh_terms: D045744:Cell Line, Tumor; D002470:Cell Survival; D022082:Cellular Structures / Q000473:pathology; D004307:Dose-Response Relationship, Radiation; D005109:Extracellular Matrix / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects; D006801:Humans; D008527:Medulloblastoma / Q000473:pathology / Q000601:surgery* / Q000628:therapy*; D008954:Models, Biological; D009361:Neoplasm Invasiveness / Q000473:pathology*; D009368:Neoplasm Transplantation / Q000379:methods; D011836:Radiation Tolerance; D013997:Time Factors