title: [Which methods to minimize the time factor are substantiated by the evidence, which are unproven?].
abstract: BACKGROUND
  Several experimental studies and randomized clinical trials demonstrate a decrease of local tumor control with increasing overall treatment time of fractionated radiotherapy. Proliferation of clonogenic tumor cells most likely is the major mechanism underlying this phenomenon. Important progress in radiation oncology might therefore be expected from inhibition of proliferation of clonogenic cells during radiation treatment.
  
  
  METHODS
  Possibilities to minimize the time factor are briefly discussed.
  
  
  CONCLUSIONS
  Inhibition of proliferation of clonogenic tumor cells during irradiation by simultaneous chemotherapy, by inhibition of signal transduction pathways that stimulate proliferation, or by pharmacological inhibition of angiogenesis are scientifically interesting but currently not proven to be effective to counteract the loss of local tumor control with increasing overall treatment of fractionated irradiation. At present, the only established approach is to complete radiotherapy within a short overall treatment time, e.g. by accelerated fractionation and by prevention or compensation of unscheduled treatment gaps.
authors.affiliation: St. Bartholomew's and the Royal London School of Medicine and Dentistry, Queen Mary & Westfield College, University of London. k.r.trott@mds.qmw.ac.uk
authors.forename: K R
authors.initials: KR
authors.lastname: Trott
authors.forename: M
authors.initials: M
authors.lastname: Baumann
mesh_terms: D020533:Angiogenesis Inhibitors; D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage*; D018906:Antineoplastic Agents, Alkylating / Q000008:administration & dosage / Q000627:therapeutic use; D003131:Combined Modality Therapy; D003520:Cyclophosphamide / Q000008:administration & dosage / Q000627:therapeutic use; D019583:Dose Fractionation, Radiation; D066246:ErbB Receptors / Q000037:antagonists & inhibitors; D005260:Female; D006801:Humans; D008297:Male; D051379:Mice; D009369:Neoplasms / Q000188:drug therapy* / Q000473:pathology / Q000532:radiotherapy*; D009389:Neovascularization, Pathologic; D011182:Postoperative Care; D011879:Radiotherapy Dosage; D012513:Sarcoma, Experimental / Q000188:drug therapy / Q000473:pathology; D015398:Signal Transduction / Q000187:drug effects / Q000528:radiation effects; D013997:Time Factors
chemical_list: D020533:Angiogenesis Inhibitors; D000970:Antineoplastic Agents; D018906:Antineoplastic Agents, Alkylating; D003520:Cyclophosphamide; D066246:ErbB Receptors