Residual vein thrombosis for assessing the optimal duration of low-molecular weight heparin after cancer-related deep vein thrombosis: The Cancer Dacus Study

BACKGROUND: Type and duration of anticoagulation is still matter of debate in cancer patients with acute Deep Vein Thrombosis (DVT) of the lower limbs. Residual Vein Thrombosis (RVT) has been proven to be effective for assessing the optimal duration of oral anticoagulants in non cancer patients (Siragusa S et al. Blood 2008:112:511-5). In the present study we evaluate the role of a RVT-based management of anticoagulation with Low-Molecular Weight Heparin in cancer patients with acute DVT. MATERIALS AND METHODS: Cancer patients with a first episode of DVT Were treated with LMWH at therapeutic dosage for 1 month followed By dose reduction of 25% in the next 5 months. At this time, they were managed according to RVT findings: those with RVT were randomized to continue anticoagulants for 6 additional months (Group A1) or to stop (Group A2), while patients without RVT stopped LMWH (Group B). Outcomes were recurrent venous thromboembolism and/or major bleeding. RESULTS: Over a period of 18 months, 134 patients were evaluated across 12 centers in Italy; total duration of follow-up was 30.5 years and median duration of follow-up was 1.2 + 0.2 years. RVT was detected in 92 (68.6%) patients; recurrent events occurred in 23.4% of those who discontinued and 15.5% of those who continued LMWH (Figure 1). The adjusted Hazard Ratio (HR) for age and sex (Group A2 vs A1) was 1.58 (95% confidence interval [CI], 0.85-2.93; p=0.145). Of the 42 (31.3%) patients without RVT , one had a recurrence (2.3%) (Figure 1). The adjusted HR (B vs A1) was 4.54 (CI 2.3-6.66; p=0.028). One major bleeding event occurred in each group of patients who stopped (Group A2 and B) and 2 in those who continued anticoagulation. Overall, 31 (23.1%) patients died due to cancer progression after a median followup of 13.2 months after randomization. CONCLUSIONS: The Cancer DACUS is the first study evaluating an individual marker for assessing duration Of anticoagulation in active cancer population. This interim analysis Shows that absence of RVT identifies a group of patients at low risk for recurrent thrombosis who can safely stop LMWH after 6 months.