Abstract
BACKGROUND: The choice of the appropriate perioperative thromboprophylaxis for people with cancer depends on the relative benefits and harms of different anticoagulants. OBJECTIVES: To systematically review the evidence for the relative efficacy and safety of anticoagulants for perioperative thromboprophylaxis in people with cancer. SEARCH METHODS: This update of the systematic review was based on the findings of a comprehensive literature search conducted on 14 June 2018 that included a major electronic search of Cochrane Central Register of Controlled Trials (CENTRAL, 2018, Issue 6), MEDLINE (Ovid), and Embase (Ovid); handsearching of conference proceedings; checking of references of included studies; searching for ongoing studies; and using the 'related citation' feature in PubMed. SELECTION CRITERIA: Randomized controlled trials (RCTs) that enrolled people with cancer undergoing a surgical intervention and assessed the effects of low-molecular weight heparin (LMWH) to unfractionated heparin (UFH) or to fondaparinux on mortality, deep venous thrombosis (DVT), pulmonary embolism (PE), bleeding outcomes, and thrombocytopenia. DATA COLLECTION AND ANALYSIS: Using a standardized form, we extracted data in duplicate on study design, participants, interventions outcomes of interest, and risk of bias. Outcomes of interest included all-cause mortality, PE, symptomatic venous thromboembolism (VTE), asymptomatic DVT, major bleeding, minor bleeding, postphlebitic syndrome, health related quality of life, and thrombocytopenia. We assessed the certainty of evidence for each outcome using the GRADE approach (GRADE Handbook). MAIN RESULTS: Of 7670 identified unique citations, we included 20 RCTs with 9771 randomized people with cancer receiving preoperative prophylactic anticoagulation. We identified seven reports for seven new RCTs for this update.The meta-analyses did not conclusively rule out either a beneficial or harmful effect of LMWH compared with UFH for the following outcomes: mortality (risk ratio (RR) 0.82, 95% confidence interval (CI) 0.63 to 1.07; risk difference (RD) 9 fewer per 1000, 95% CI 19 fewer to 4 more; moderate-certainty evidence), PE (RR 0.49, 95% CI 0.17 to 1.47; RD 3 fewer per 1000, 95% CI 5 fewer to 3 more; moderate-certainty evidence), symptomatic DVT (RR 0.67, 95% CI 0.27 to 1.69; RD 3 fewer per 1000, 95% CI 7 fewer to 7 more; moderate-certainty evidence), asymptomatic DVT (RR 0.86, 95% CI 0.71 to 1.05; RD 11 fewer per 1000, 95% CI 23 fewer to 4 more; low-certainty evidence), major bleeding (RR 1.01, 95% CI 0.69 to 1.48; RD 0 fewer per 1000, 95% CI 10 fewer to 15 more; moderate-certainty evidence), minor bleeding (RR 1.01, 95% CI 0.76 to 1.33; RD 1 more per 1000, 95% CI 34 fewer to 47 more; moderate-certainty evidence), reoperation for bleeding (RR 0.93, 95% CI 0.57 to 1.50; RD 4 fewer per 1000, 95% CI 22 fewer to 26 more; moderate-certainty evidence), intraoperative transfusion (mean difference (MD) -35.36 mL, 95% CI -253.19 to 182.47; low-certainty evidence), postoperative transfusion (MD 190.03 mL, 95% CI -23.65 to 403.72; low-certainty evidence), and thrombocytopenia (RR 3.07, 95% CI 0.32 to 29.33; RD 6 more per 1000, 95% CI 2 fewer to 82 more; moderate-certainty evidence). LMWH was associated with lower incidence of wound hematoma (RR 0.70, 95% CI 0.54 to 0.92; RD 26 fewer per 1000, 95% CI 39 fewer to 7 fewer; moderate-certainty evidence). The meta-analyses found the following additional results: outcomes intraoperative blood loss (MD -6.75 mL, 95% CI -85.49 to 71.99; moderate-certainty evidence); and postoperative drain volume (MD 30.18 mL, 95% CI -36.26 to 96.62; moderate-certainty evidence).In addition, the meta-analyses did not conclusively rule out either a beneficial or harmful effect of LMWH compared with Fondaparinux for the following outcomes: any VTE (DVT or PE, or both; RR 2.51, 95% CI 0.89 to 7.03; RD 57 more per 1000, 95% CI 4 fewer to 228 more; low-certainty evidence), major bleeding (RR 0.74, 95% CI 0.45 to 1.23; RD 8 fewer per 1000, 95% CI 16 fewer to 7 more; low-certainty evidence), minor bleeding (RR 0.83, 95% CI 0.34 to 2.05; RD 8fewer per 1000, 95% CI 33 fewer to 52 more; low-certainty evidence), thrombocytopenia (RR 0.35, 95% CI 0.04 to 3.30; RD 14 fewer per 1000, 95% CI 20 fewer to 48 more; low-certainty evidence), any PE (RR 3.13, 95% CI 0.13 to 74.64; RD 2 more per 1000, 95% CI 1 fewer to 78 more; low-certainty evidence) and postoperative drain volume (MD -20.00 mL, 95% CI -114.34 to 74.34; low-certainty evidence) AUTHORS' CONCLUSIONS: We found no difference between perioperative thromboprophylaxis with LMWH versus UFH and LMWH compared with fondaparinux in their effects on mortality, thromboembolic outcomes, major bleeding, or minor bleeding in people with cancer. There was a lower incidence of wound hematoma with LMWH compared to UFH.