Anticoagulation for the intial treatment of venous thromboembolism in patients with cancer

Low molecular weight heparin may have a small effect on mortality compared to unfractionated heparin in the initial treatment of venous thromboembolism in patients with cancer.

The quality of evidence is downgraded by indirectness (results are based on subgroup analyses), and by imprecise results (wide confidence intervals and few outcome events).

Summary

A Cochrane review included 15 studies with a total of 1 615 subjects with cancer and venous thromboembolism (VTE). 13 studies (n=1 025) compared low molecular weight heparin (LMWH) with unfractionated heparin (UFH), one (n=477) compared fondaparinux with UFH and LMWH, and one (n=113) compared dalteparin with tinzaparin.

LMWH decreased statistically insignificantly mortality at 3 months compared to UFH (RR 0.66, 95% CI 0.40 to 1.10; 5 studies, n=418), and did not rule out a clinically significant increase or decrease in VTE recurrence (RR 0.69, 95% CI 0.27 to 1.76; 3 studies, n=422). There was no differences between fondaparinux and heparin (UFH or LMWH) for the outcomes of mortality at 3 months (RR 1.25, 95% CI 0.86 to 1.81; 1 study, n=477), recurrent VTE (RR 0.93, 95% CI 0.56 to 1.54; 1 study, n=477), major bleeding (RR 0.82, 95% CI 0.40 to 1.66; 1 study, n=477), or minor bleeding (RR 1.53, 95% CI 0.88 to 2.66; 1 study, n=477). The study comparing dalteparin with tinzaparin did not find differences in mortality (RR 0.86, 95% CI 0.43 to 1.73; 1 study, n=113), recurrent VTE (RR 0.44, 95% CI 0.09 to 2.16; 1 study, n=113), major bleeding (RR 2.19, 95% CI 0.20 to 23.42; 1 study, n=113), or minor bleeding (RR 0.82, 95% CI 0.30 to 2.21; 1 study, n=113).