The Effect of Anticoagulant Therapy on Survival and Outcome of Venous Thrombosis in Children, Teenagers, and Young Adults with Acute Lymphoblastic Leukemia Treated According to ALL-MB-2008 and ALL-MB-2015 Protocols

Abstract

Aim. To assess the effect of anticoagulant therapy on survival and outcome of venous thrombosis in children, teenagers, and young adults with acute lymphoblastic leukemia (ALL). Materials & Methods. Venous thrombosis was diagnosed in 42 out of 592 ALL patients treated according to ALL-MB-2008 and ALL-MB-2015 protocols from 2008 to 2017. Results. A daily dose of 150-200 lU/kg low molecular weight heparin (LMWH) was administered to 30 patients. Duration of anticoagulant treatment was up to 1 month in 4 patients, 2-3 months in 8 patients, 4-6 months in 12 patients, and 7-12 months in 4 patients. To 2 patients anticoagulants were administered for more than 24 months. Complete recanalization of thrombosed vessel was achieved in 19 patients, partial recanalization was achieved in 6 patients, obliteration of predominantly internal jugular vein was found in 5 patients. During thrombocytopenia (100 to 35 x 10<sup>9</sup>/L) 12 patients received reduced doses of LMWH for 1-4 weeks. In the period of chemotherapy-induced thrombocytopenia the daily LMWH dose was reduced in proportion to thrombocyte level. After thrombocyte recovery up to more than 100 x 10<sup>9</sup>/L antithrombotic treatment was continued with LMWH daily dose of 150-200 anti-Xa lU/kg. The duration of anticoagulant treatment among 12 patients who received reduced doses of LMWH was up to 1 month in 3 patients, 2-3 months in 4 patients, 4-6 months in 3 patients, and 7-12 months in 2 patients. Complete recanalization of thrombosed vessel was achieved in 8 patients, partial recanalization was achieved in 2 patients, vein obliteration was found in 2 patients. No correlation between LMWH dosage and thrombosis outcome was observed (χ<sup>2</sup> = 0.494; p = 0.78). Maintenance (accompanying) therapy was completed in 38 out of 42 ALL patients with venous thrombosis. Event-free survival was 83 ± 8 %, that was similar to the one (81 ± 2 %) in patients without thrombosis (p = 0.654). Conclusion. Anticoagulant treatment of venous thrombosis complicating ALL in children, teenagers, and young adults did not yield a decrease of either overall or event-free survival. Reduction of LMWH doses in the period of chemotherapy-induced thrombocytopenia did not affect the outcome of venous thrombosis.