title: A critical review of the use of vincristine (VCR) as a tumour cell synchronizing agent in cancer therapy.
abstract: Vincristine (VCR) has been used clinically in so-called 'tumour cell synchronization therapy schedules'. These schedules are based on the assumption that cells, arrested in metaphase by low doses of VCR, subsequently re-enter the proliferative cycle synchronously. However, the evidence that tumour cell synchrony can be achieved under clinical conditions or that 'cell synchronization therapy schedules' yield a better therapeutic response than other efficient combination schemes, is scanty. Further, even in experimental systems, the efficacy of VCR as a cell synchronizing agent is disputed. Indeed, in some systems, cells arrested in metaphase by low doses of VCR, do not re-enter a normal proliferative cycle at all following arrest. In addition, the complex nature of the VCR-tumour interaction and the heterogeneous nature of the tumour cell populations against which it is used augurs badly for the successful application of cell synchronization therapy schedules.
mesh_terms: D000818:Animals; D002453:Cell Cycle / Q000187:drug effects*; D003520:Cyclophosphamide / Q000627:therapeutic use; D003584:Cytological Techniques; D004359:Drug Therapy, Combination; D006801:Humans; D007399:Interphase / Q000187:drug effects; D007700:Kinetics; D008677:Metaphase / Q000187:drug effects; D008727:Methotrexate / Q000627:therapeutic use; D051379:Mice; D009369:Neoplasms / Q000188:drug therapy / Q000473:pathology*; D014750:Vincristine / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use
chemical_list: D014750:Vincristine; D003520:Cyclophosphamide; D008727:Methotrexate