Editor's Choice - A Systematic Review and Meta-Analysis of the Efficacy and Safety of Anticoagulation in the Treatment of Venous Thromboembolism in Patients with Cancer.

OBJECTIVE/BACKGROUND: The aim was to review the relative efficacy and safety of anticoagulation for managing venous thromboembolism (VTE) in patients with cancer.

METHODS: A systematic review and meta-analysis was carried out. On 17 May 2018 the MEDLINE and Scopus databases were searched for randomised controlled trials (RCTs). Eligible RCTs had to be performed in patients with cancer exclusively or to report results on a subset of patients with cancer. The main study outcomes (efficacy/recurrent VTE and safety/bleeding events) were expressed as risk ratios (RR) with a 95% confidence interval (CI). The quality of evidence was assessed following the GRADE method.

RESULTS: Twenty-three RCTs with 6980 patients were identified. Low molecular weight heparins (LMWHs) were more effective than vitamin K antagonists (VKAs) in preventing recurrent VTE (RR 0.58, 95% CI 0.45-0.75) and deep vein thrombosis (RR 0.44, 95% CI 0.29-0.69) but not pulmonary embolism (PE), bleeding, or overall mortality. Direct oral anticoagulants (DOACs) were more effective than VKAs in preventing recurrent VTE (RR 0.65, 95% CI 0.45-0.95) but not DVT, PE, overall mortality, or bleeding. However, anti-Xa DOACs were more effective (RR for VTE 0.64, 95% CI 0.42-0.97) and caused less bleeding than VKAs, although major bleeding was reduced only with DOACs not requiring initial parenteral anticoagulation (RR 0.45, 95% CI 0.21-0.97). In a direct comparison, DOACs were more effective than LMWHs in preventing VTE recurrence (RR 0.64, 95% CI 0.45-0.90) but caused more major bleeding (RR 1.75, 95% CI 1.10-2.77), with no difference in fatal bleeding and overall mortality. Quality of evidence, where sufficient, was mostly moderate or high.

CONCLUSION: Compared with VKAs, LMWHs and DOACs are more effective in treating VTE, but the former caused less bleeding. DOACs are more effective than LMWHs in preventing VTE recurrence but may carry a higher risk of major bleeding, pending additional information by ongoing trials.