Long-term Treatment for Cancer Patients With Deep Venous Thrombosis or Pulmonary Embolism

Background Patients with cancer and a first deep venous thrombosis of the leg or pulmonary embolism (venous thromboembolism, VTE) are generally treated with low molecular weight heparin (LMWH)injections for 6 months, since this treatment is associated with a reduced incidence of recurrent VTE compared to vitamin K antagonists (VKA). It is recommended that patients with active malignancy (metastatic cancer and/or ongoing cancer treatment)continue anticoagulant treatment. However, it is unknown whether LMWH is still superior compared to VKA for the long-term anticoagulant treatment. Aim The aim of this study is to evaluate whether low-molecular-weight heparin more effectively reduces recurrent VTE compared to vitamin K antagonists in patients with cancer who have already completed 6 to 12 months of anticoagulant treatment because of deep venous thrombosis of the leg or pulmonary embolism. Hypothesis The investigators hypothesize that LMWH is more effective compared to VKA in the long-term treatment of VTE in cancer patients who have already been treated for 6-12 months with anticoagulants. Design This is a multicenter, multinational, randomized, open label trial. Patients Patients with a malignancy (all types, solid and hematological) who have received 6-12 months of anticoagulation for VTE and have an indication for continuing anticoagulation, will be randomly assigned to six additional months of LMWH or VKA. LMWH will be administered in a weight-adjusted scheme, with 65-75% of therapeutic doses. All types of LMWH and VKA are allowed, as long as weight adjusted dosing is possible for LMWH. The target INR will be 2.0-3.0. The primary efficacy outcome is symptomatic recurrent VTE, i.e. deep vein thrombosis and pulmonary embolism. The primary safety outcome is major bleeding. Sample size A total of 65 to 87 recurrent VTE events are needed to show a 50% reduction with LMWH as compared to VKA (type I error 0.05, two-sided, power respectively 80 and 90%). To obs