Background Central venous catheter (CVC) placement increases the risk of thrombosis in cancer patients. Thrombosis often necessitates the removal of the CVC, resulting in treatment delays and thrombosis related morbidity and mortality. Objectives To evaluate the efficacy and safety of anticoagulation in cancer patients with a CVC. Search strategy We searched The Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 1 2010), MEDLINE (January 1966 to February 2010; accessed via OVID), EMBASE (January 1980 to February 2010; accessed via OVID) and ISI the Web of Science (1975 to February 2010). We handsearched conference proceedings, checked references of included studies and used the "related article" feature within PubMed. Selection criteria Randomized controlled trials (RCTs) comparing any dose of unfractionated heparin (UFH), low molecular weight heparin (LMWH), vitamin K antagonists (VKA), or fondaparinux to no intervention or placebo or comparing two different anticoagulants in cancer patients with a CVC. Data collection and analysis Two authors independently extracted data from each included study and resolved their disagreements by discussion. Main results Of 8187 identified citations, we included 12 RCTs enrolling 3611 patients and assessing either prophylactic dose heparin or low dose VKAs. Prophylactic dose heparin was not associated with a statistically significant effect on death (relative risk (RR) = 0.85; 95% confidence interval (CI): 0.53 to 1.37), symptomatic deep venous thrombosis (DVT) (RR = 0.54; 95% CI: 0.28 to 1.05) asymptomatic DVT (RR = 0.81; 95% CI: 0.64 to 1.02), major bleeding (RR = 0.68; 95% CI: 0.10 to 4.78), thrombocytopenia (RR = 0.85; 95% CI: 0.49 to 1.46), or infection (RR = 0.91; 95% CI: 0.49 to 1.68). Similarly, low dose VKAs were not associated with a statistically significant effect on death (RR = 0.97; 95% CI: 0.82 to 1.15), symptomatic DVT (RR = 0.63; 95% CI: 0.35 to 1.11) or major bleeding (RR = 6.93; 95% CI: 0.86 to 56.08). However, they were associated with a statistically significant reduction in asymptomatic DVT (RR = 0.42; 95% CI: 0.28 to 0.61). Studies comparing heparin to VKA found no effects on any of the outcomes of interest. Authors' conclusions We found no statistically significant effect of heparin or VKA on the outcomes of interest. However, the findings did not rule out clinically important benefits and harms. Patients with cancer with CVCs considering anticoagulation should balance the possible benefit of reduced thromboembolic complications with the possible harms and burden of anticoagulants.
