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Absence of Residual Thrombosis After 6 Months of Low–Molecular Weight Heparin Indicates Low Risk for Recurrent Cancer-Related Deep-Vein Thrombosis

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Key Points

  • Patients without residual vein thrombosis after 6 months of low–molecular weight heparin were at low risk of recurrent venous thromboembolism over the next 12 months.
  • In patients with residual vein thrombosis after 6 months of low–molecular weight heparin, continuing treatment for an additional 6 months did not significantly reduce risk of recurrent venous thromboembolism.

In an Italian study (Cancer-DACUS) reported in the Journal of Clinical Oncology, Napolitano et al found that patients with no residual vein thrombosis after 6 months of low–molecular weight heparin for a first episode of cancer-related deep-vein thrombosis of the lower limbs had low risk for recurrent thrombotic events in the absence of additional low–molecular weight heparin treatment. They also found that an additional 6 months of treatment in those with residual vein thrombosis did not reduce risk of recurrent thrombotic events.

Study Details

In the study, 347 patients with active cancer and a first episode of deep-vein thrombosis treated with low–molecular weight heparin for 6 months enrolled between October 2005 and April 2010 were managed according to presence or absence of residual vein thrombosis. Those with residual vein thrombosis were randomly assigned to continue low–molecular weight heparin for an additional 6 months (n = 119) or to discontinue treatment (n = 123), and those without residual vein thrombosis stopped treatment (n = 105). The primary endpoint was recurrent venous thromboembolism during the 1 year after discontinuation of low–molecular weight heparin, and the secondary endpoint was major bleeding.

Risk of Recurrence

The 12-month cumulative recurrent venous thromboembolism rates were 21.9% in the 6-month low–molecular weight heparin/residual vein thrombosis group vs 18.5% in the 12-month group; after adjustment for age, sex, previous surgery, and presence of metastasis, the hazard ratio was 1.37 (P = .311). The 12-month cumulative venous thromboembolism rate in the no–residual vein thrombosis group was 2.8%, with an adjusted hazard ratio of 6.0 (P = .005) for the 12-month low–molecular weight heparin/residual vein thrombosis group vs the no–residual vein thrombosis group.

In the 12-month low–molecular weight heparin/residual vein thrombosis, 6-month low–molecular weight heparin/residual vein thrombosis, and no–residual vein thrombosis groups, isolated deep-vein thrombosis accounted for 50%, 70%, and 67% of events (P = .379), deep-vein thrombosis and pulmonary embolism accounted for 39%, 26%, and 0% (P = .333), and pulmonary embolism alone accounted for 11%, 4%, and 33% (P = .183).

Bleeding Risk

Major bleeding events occurred in 5.8% of the 12-month low–molecular weight heparin/residual vein thrombosis group, 1.6% of the 6-month low–molecular weight heparin/residual vein thrombosis group, and 1.9% of the no–residual vein thrombosis group (P = .109). Minor bleeding occurred in 7.6%, 6.5%, and 4.8% (P = .689). A total of 12.1% of patients died during follow-up, all due to cancer progression. No fatal pulmonary embolisms were observed.

The investigators concluded: “In patients with cancer with a first [deep-vein thrombosis], treated for 6 months with [low–molecular weight heparin], absence of [residual vein thrombosis] identifies a population at low risk for recurrent thrombotic events. Continuation of [low–molecular weight heparin] in patients with [residual vein thrombosis] up to 1 year did not reduce recurrent [venous thromboembolism].”

Sergio Siragusa, MD, of Universitá degli Studi di Palermo, is the corresponding author for the Journal of Clinical Oncology article.

The authors indicated no potential conflicts of interest.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.


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