Clinical relevance of genetic risk factors for thrombosis in paediatric oncology patients with central venous catheters

We prospectively evaluated the clinical relevance of genetic risk factors o f thrombosis in 137 paediatric patients with solid tumours or leukaemia/lym phoma. The factor V G1691A (FV-L), the prothrombin G20210A (FII-L) and the homozygous MTHFR variant were examined. In addition, protein C, protein S a nd antithrombin (AT) deficiency were evaluated in patients with ALL or thro mbosis. The inter-group incidence of risk factors and thrombotic events was compared. 73 of the 137 patients had ALL and 64 another form of leukaemia, lymphoma or a solid tumour. They were treated according to the established paediatric tumour protocols ALL-BFM, NHL-BFM, COSS, CWS and others. All pa tients had central venous lines. No patient received heparin or any other a nticoagulant. Endpoints of the study were thrombosis, regular completion of chemotherapy or death. Incidence of mutations in the whole group: FV-L (7. 3% heterozygous, 0.7% homozygous); FII-L (2.9% heterozygous, no homozygotes ); MTHFR (51.8% heterozygous, 10.9% homozygous). Ten patients (7.3%), 6 wit h ALL and 4 with solid tumours, developed thrombosis. 4 of the 6 patients w ith ALL and thrombosis (67%) but only 21% of ALL patients without thrombosi s had a genetic risk factor (P < 0.013, chi(2)). No genetic defect was foun d in the 4 patients with other malignancies and thrombosis,. However, besid es a tumour, these patients had additional exogenous risk factors including diabetes insipidus and hemiparesis. Conclusion Genetic mutations appear to be additional risk factors for the d evelopment of thrombosis in patients with ALL. In contrast, these mutations do not appear to be relevant risk factors for thrombosis in the small numb er of children with other malignant diseases reported here. This difference map be due to asparaginase and corticosteroids being used in ALL but not i n solid tumour protocols.