title: Multicellular tumour spheroids in radiation biology.
abstract: OBJECTIVE
  Multicellular tumour spheroids are being used with increasing frequency in various aspects of tumour biology, including studies dealing with radiation biology. This review attempts to outline recent studies using these three-dimensional systems in radiation biology with particular reference made to papers testing radiotherapeutic protocols with spheroids.
  
  
  BACKGROUND
  Multicellular tumour spheroids are three-dimensional structures composed of cancer cells. They are formed from monolayer tumour cells when these are grown by various in vitro methods (e.g. liquid-overlay, spinner flask and gyratory rotation systems). Because of the cellular organization in spheroids, they have been often shown to recreate in vivo tumours much more closely than two-dimensional in vitro models.
  
  
  CONCLUSIONS
  Because of their particular architectural characteristics, multicellular spheroids are demonstrated to be extremely useful in testing radiotherapeutic protocols, including dose rate and fractionation, radioimmunotherapy and the effects of combined treatments (e.g. radiation and anti-neoplastic drugs). Further studies should seek not only to continue testing these protocols, but also to investigate the more fundamental questions of radiation-induced apoptotic cell death, cell-cycle events, cell-cell interactions and cell adhesion phenomena.
authors.affiliation: Laboratorio di Ultrastrutture, Istituto Superiore di Sanità, Rome, Italy. mariateresa.santini@iss.it
authors.forename: M T
authors.initials: MT
authors.lastname: Santini
authors.forename: G
authors.initials: G
authors.lastname: Rainaldi
authors.forename: P L
authors.initials: PL
authors.lastname: Indovina
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D018929:Cell Culture Techniques / Q000379:methods; D003131:Combined Modality Therapy; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D008855:Microscopy, Electron, Scanning; D009374:Neoplasms, Experimental / Q000188:drug therapy / Q000532:radiotherapy / Q000628:therapy; D011853:Radiobiology; D016499:Radioimmunotherapy; D018874:Spheroids, Cellular / Q000187:drug effects / Q000528:radiation effects* / Q000648:ultrastructure
chemical_list: D000970:Antineoplastic Agents