Venous thromboembolism (VTE) presents a significant challenge for cancer patients and their physicians.
VTE includes deep-vein thrombosis, a blood clot that forms in a major vein of the leg or in the arms, pelvis, or other large veins in the body, as well as pulmonary embolism, a potentially deadly condition that occurs when the clot breaks off and travels to the lungs.
While current clinical practice guidelines recommend the use of low-molecular-weight heparins (LMWH) rather than warfarin to reduce this risk, recommendations were based largely on a single trial.
Given the lack of confirmatory trials or trials including different medications, warfarin remains a commonly used anticoagulant treatment in cancer patients.
To confirm previous findings that LMWH is superior to warfarin in preventing recurrent VTE among cancer patients, researchers enrolled 900 cancer patients with DVT or PE in a randomised, Phase III trial evaluating the efficacy and safety of the LMWH tinzaparin.
Participants received either tinzaparin once daily for six months or tinzaparin once daily for five to 10 days followed by six months of warfarin.
During the treatment period, 31 patients (6.9%) treated with tinzaparin experienced recurrent VTE compared with 45 (10%) patients treated with warfarin.
While tinzaparin did not meet statistical significance in reducing recurrent VTE, the drug showed statistically significant activity in reducing recurrent DVT in veins above the knee.
Researchers did not observe a difference in the mortality or incidence of major bleeding events (2.9% in the tinzaparin arm and 2.7% in the warfarin arm), but noted that significantly fewer patients experienced clinically relevant, non-major bleeding with tinzaparin than warfarin (11% vs 16%).
“As the largest randomised, controlled trial on the treatment of thrombosis among cancer patients, this study reinforces clinical guidelines supporting the use of low-molecular-weight heparins instead of warfarin to prevent recurrent blood clots,” said lead study author Agnes Lee, MD, of the University of British Columbia in Vancouver, Canada.
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