Anticoagulation in patients with cancer: an overview of reviews

INTRODUCTION: Relative benefits and harms of anticoagulants are required for judgments regarding appropriate anticoagulation in patients with cancer. OBJECTIVES: To review the benefits and harms of anticoagulants for prophylactic, therapeutic, and survival improvement indications in patients with cancer. PATIENTS AND METHODS: Overview of 6 systematic reviews of anticoagulation in cancer following the Cochrane Collaboration and Grading of Recommendations Assessment, Development and Evaluation methodology. RESULTS: Central venous catheters thromboprophylaxis with heparin or warfarin does not significantly reduce the incidence of symptomatic deep vein thrombosis (DVT) (relative risk [RR] 0.43, 95% CI 0.18-1.06 and RR 0.62, 95% CI 0.30-1.27 respectively). For perioperative thromboprophylaxis, low-molecular-weight heparin (LMWH) and unfractionated heparin (UFH) have similar effects on mortality (RR 0.89, 95% CI 0.61-1.28) and morbidity outcomes. For the initial treatment of venous thromboembolism (VTE), LMWH compared with UFH reduces mortality at 3 months (RR 0.71, 95% CI 0.52-0.98). For the long-term treatment of VTE, LMWH compared with vitamin K antagonists reduces VTE recurrence (hazard ratio [HR] 0.47, 95% CI 0.32-0.71) but not mortality (HR 0.96, 95% CI 0.81-1.14). As interventions to improve survival, warfarin suggests a survival benefit at 6 months in the subgroup of small cell lung cancer (SCLC) (RR 0.69, 95% CI 0.50-0.96) while heparin suggests a survival benefit in patients with cancer in general (HR 0.77, 95% CI 0.65-0.91) and in those with limited SCLC in particular (HR 0.56, 95% CI 0.38-0.83). CONCLUSIONS: In patients with cancer, current evidence does not support routine use of thromboprophylaxis for central venous catheters or a specific anticoagulant for perioperative thromboprophylaxis. Anticoagulants may improve survival, but more data will be useful in deciding which subgroups benefit most.