Low rate of severe venous thromboses in children with ALL treatment according to COALL-92 and-97 protocol

Venous thromboses (VT) in children with ALL who were treated according to t he COALL-89 protocol were reported to occur with a frequency of 2.1% (6/286 ). 4/6 of the reported VT were catheter related. However, in other cohorts of ALL patients treated according to American protocols the incidence of se vere thromboses was 2-11%. Most of the VT were not catheter related, but we re atypical thromboses like sinus venous thromboses. In these patients here ditary thrombophilia risk factors seemed to play a major role. In a 6 year period including the COALL protocols -92 and -97 only 10/684 (1.5%) childre n presented with symptomatic VT, and 7/10 thromboses were catheter related. Every thrombotic event could be successfully treated either by heparin adm inistration or fibrinolytic agents. 2/10 VT were secondary due to a septic event. 5 out of 8 primary VT occurred after asparaginase/dexamethasone appl ication during the reinduction therapy. In conclusion, symptomatic thrombot ic events are very rare in the COALL studies. Important risk factors for de velopment of VT appeared to be central lines, asparaginase application and infectious/septic complications. However, the role of genetic risk factors of thrombosis in these patients has still to be determined.