title: The multi-step nature of carcinogenesis and the implications for risk analysis.
abstract: OBJECTIVE
  For the purposes of constructing biologically realistic models of radiation cancer risk it is necessary to have detailed knowledge of the post-irradiation mechanisms involved.
  
  
  METHODS
  This brief review considers selected aspects of DNA damage response, tumour initiation/development, together with attendant factors and provides comment on the implications for cancer risk estimation and some of the uncertainties that remain.
  
  
  CONCLUSIONS
  It is judged from studies with animal models that, in the main, radiation tumorigenesis proceeds in a conventional multi-step fashion following radiation-induced specific gene losses from single-target stem cells.
authors.affiliation: National Radiological Protection Board, Chilton, Didcot, Oxon, UK.
authors.forename: R
authors.initials: R
authors.lastname: Cox
mesh_terms: D000818:Animals; D015197:Carcinogenicity Tests; D002453:Cell Cycle / Q000528:radiation effects; D004247:DNA / Q000528:radiation effects*; D004249:DNA Damage; D004260:DNA Repair; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D008954:Models, Biological; D009381:Neoplasms, Radiation-Induced / Q000209:etiology* / Q000235:genetics; D018570:Risk Assessment; D014407:Tumor Cells, Cultured / Q000528:radiation effects
chemical_list: D004247:DNA