Optimal Duration of Low Molecular Weight Heparin for the Treatment of Cancer-Related Deep Vein Thrombosis: The Cancer-DACUS Study

PURPOSE: We evaluated the role of residual vein thrombosis (RVT) to assess the optimal duration of anticoagulants in patients with cancer who have deep vein thrombosis (DVT) of the lower limbs. PATIENTS AND METHODS: Patients with active cancer and a first episode of DVT treated with low molecular weight heparin (LMWH) for 6 months were eligible. Patients were managed according to RVT findings: those with RVT were randomly assigned to continue LMWH for an additional 6 months (group A1) or to discontinue it (group A2), and patients without RVT stopped LMWH (group B). The primary end point was recurrent venous thromboembolism (VTE) during the 1 year after disconinuation of LMWH, and the secondary end point was major bleeding. Analyses are from the time of random assignment. RESULTS: Between October 2005 and April 2010, 347 patients were enrolled. RVT was detected in 242 patients (69.7%); recurrence occurred in 22 of the 119 patients in group A1compared with 27 of 123 patients in group A2. The adjusted hazard ratio (HR) for group A2 versus A1 was 1.37 (95% CI, 0.7 to 2.5; P = .311). Three of the 105 patients in group B developed recurrent VTE; adjusted HR for group A1 versus B was 6.0 (95% CI, 1.7 to 21.2; P = .005). Three major bleeding events occurred in group A1, and two events each occurred in groups A2 and B. The HR for major bleeding in group A1 versus group A2 was 3.78 (95% CI, 0.77 to 18.58; P = .102). Overall, 42 patients (12.1%) died during follow-up as a result of cancer progression. CONCLUSION: In patients with cancer with a first DVT, treated for 6 months with LMWH, absence of RVT identifies a population at low risk for recurrent thrombotic events. Continuation of LMWH in patients with RVT up to 1 year did not reduce recurrent VTE.