Anticoagulation for the Treatment of Cancer-Associated Thrombosis: A Systematic Review and Network Meta-Analysis of Randomized Trials

To perform a systematic review and network meta-analysis evaluating the efficacy and safety of low-molecular-weight heparins (LMWHs), vitamin K antagonists (VKAs), and direct-acting oral anticoagulants (DOACs) for the treatment of cancer-associated thrombosis (CAT). We searched MEDLINE, Cochrane Central Register of Controlled Trials, and conference abstracts through March 2018. Randomized controlled trials (RCTs) enrolling adults with CAT comparing 2 or more full-dose anticoagulants (LMWH, VKA, and DOAC) and evaluating recurrent venous thromboembolism (VTE), major bleeding, and/or all-cause mortality were included. Reviewers identified studies, extracted data, and assessed the quality of the evidence in duplicate. A frequentist network meta-analysis, which uses direct and indirect evidence to simultaneously compare multiple interventions, was performed using a random-effects approach. Results are reported as pooled relative risks (RRs) with 95% confidence intervals (CIs). We included 13 RCTs (n = 6292): 7 compared LMWHs with VKAs, 4 compared DOACs with VKAs, and 2 compared DOACs with LMWHs. The risk of recurrent VTE was significantly reduced by 28% and 54% with a DOAC compared to an LMWH and a VKA, respectively. Low-molecular-weight heparins significantly reduced the risk of recurrent VTE by 36% versus VKAs. The risk of major bleeding was 14% higher with DOACs compared to LMWHs and 15% and 25% lower with DOACs and LMWHs versus VKAs, although 95% CIs included unity for each. The risk of all-cause mortality appeared similar for all 3 comparisons (RR = 1.0 for each comparison). Direct-acting oral anticoagulants appeared superior in reducing recurrent VTE in patients with CAT compared to LMWH and VKAs, but an increased risk of major bleeding versus LMWH cannot be ruled out.