Which Blood Thinner Is More Effective at Reducing Clot Risk in Cancer?

Venous thromboembolism (VTE) occurs when blood clots form in veins. Its most common forms are deep vein thrombosis (DVT), usually clots in the legs, and pulmonary embolism (PE), in which these clots travel to the lungs. VTE often results from immobility or certain diseases. It is serious because pulmonary embolism can be life-threatening.

Why VTE Matters in Cancer

VTE is particularly important in cancer because patients face a higher risk than the general population. Cancer itself can cause hypercoagulation (increased blood clotting), and some treatments further increase VTE risk. VTE also complicates cancer care and reduces quality of life. Studies worldwide have found that VTE develops in 4% to 20% of cancer patients.

Managing VTE risk is therefore a crucial part of cancer care. The best strategy remains debated, however, and more research is needed. This article discusses a recent comparison of the effectiveness of different anticoagulants (blood thinners) used to manage VTE risk in cancer patients.

Which Blood Thinner?

Direct oral anticoagulants (DOACs) may carry lower risks of VTE, major bleeding, and death in cancer patients than low-molecular-weight heparin (LMWH). This conclusion comes from a comprehensive analysis published on 24 July 2023 in JAMA Network Open. The study may help doctors and patients manage VTE risk during cancer treatment.

Direct oral anticoagulants are taken by mouth and act directly on clotting factors. They are commonly prescribed to people at risk of clots or who already have clots. Examples include dabigatran (Pradaxa), rivaroxaban (Xarelto), apixaban (Eliquis), and betrixaban (Bevyxxa). Each acts at a different step in the clotting process.

Study Details

This retrospective cohort study used OptumLabs electronic records and included adults with cancer and acute VTE.

Patients were classified by the anticoagulant prescribed within 30 days of VTE onset: a DOAC, LMWH, or warfarin (Coumadin).

Follow-up continued until treatment ended. Recurrent VTE and all-cause mortality were the primary effectiveness endpoints; major bleeding events and bleeding sites were the main safety endpoints.

The analysis included 5100 patients (mean age, 66.3). Most were White (69.8%), with 15.7% Black and 7.6% Hispanic. Cancer types included lung, colorectal, gynecological, and urological cancers.

About half (49.3%) received a DOAC, 29.2% LMWH, and 28.6% warfarin.

Results

• Compared with DOACs, LMWH and warfarin increased recurrent VTE risk (hazard ratios [HRs], 1.47 and 1.46, respectively).

A “hazard ratio” (HR) indicates how much greater the risk of an event—here, recurrent VTE—is in one group (LMWH or warfarin users) compared with a control group (DOAC-treated patients).

An HR greater than 1 means higher risk in the experimental group than in the control group. An HR of 1.47, for example, indicates a 47% higher recurrent VTE risk with LMWH than with DOACs. Similarly, an HR of 1.46 indicates a 46% higher risk with warfarin than with DOACs.

• LMWH was associated with greater major bleeding risk (HR, 2.27) and all-cause mortality (HR, 1.61) than DOACs. Mortality did not differ significantly between warfarin and DOACs (HR, 1.19; 95% CI, 0.85 - 1.68).
• Compared with DOAC users, LMWH users had greater risks of hospitalization for major, gastrointestinal, and intracranial (brain) bleeding (HRs, 2.27, 1.72, and 2.72, respectively).
• Warfarin and DOAC users had similar hospitalization risks for major, gastrointestinal, and intracranial bleeding (HRs, 1.12, 1.03, and 1.04, respectively).

What Should We Take from This Study?

Consistent with recent clinical trials, these findings confirm DOACs' overall effectiveness and safety in cancer care. An association also emerged suggesting that DOAC use tends to reduce all-cause mortality. The data can support informed decisions shared by clinicians and patients and contribute to developing clinical guidelines for cancer-associated VTE treatment.