Blood thinner treatment in patients with blood clot and cancer

Patients with cancer are at higher risk to develop blood clot.  Blood clot in the leg is called deep venous trhormbosis and in the lung is called pulmonary emboli.  Clot is very serious and can be life threathening.  The treatment usually consists of giving patients blood thinner in the form of pills (Warfarin or coumadin) or injection (low molecular weight heparin such as dalteparin [Fragmin] or enoxaparin [lovenox]).

A multicenter, international, randomized clinical trial (CLOT trial) compared six months of treatment with either dalteparin or warfarin (target INR 2.0 to 3.0) in 672 patients with cancer and acute symptomatic blood clot. Dalteparin therapy was associated with a significant reduction in the cumulative rate of recurrent VTE at six months (9 versus 17 percent, hazard ratio 0.48, 95% CI 0.30-0.77). There were no significant differences in the rates of major bleeding (6 versus 4 percent), any bleeding (14 versus 19 percent), or overall mortality at six months (39 versus 41 percent) between the dalteparin and warfarin arms, respectively.  Dalterparin received approval to be used in patients with cancer and blood clot.  Please note that the patients who received coumarin in that study, only 46% were therapeutic coumarin leven, 30% were below and 24% were over the target coumarin level.

Another trial, the CANTHANOX trial compared three months of therapy with either warfarin or enoxaparin in cancer patients with bloot clot.  After 147 patients were accrued, the study concluded that warfarin was associated with a high bleeding and enoxaparin may be as effective as and safer than warfarin.

A 2008 Cochrane review of results in six randomized controlled trials in cancer patients receiving long-term treatment for VTE found no survival advantage for LMW heparin over warfarin and no difference in bleeding outcomes, but a significant reduction in VTE.

My experience show that not too many patients want to inject themselves for 3-6 months and prefer pill warfarin.   But you should discuss the pro and con with your oncologists of these 2 drugs if you have cancer and blood clot.

Reference

Lee AY, et al.  Randomized Comparison of Low-Molecular-Weight Heparin versus Oral Anticoagulant Therapy for the Prevention of Recurrent Venous Thromboembolism in Patients with Cancer (CLOT) Investigators. N Engl J Med. 2003;349(2):146.

Meyer G, et al. Comparison of low-molecular-weight heparin and warfarin for the secondary prevention of venous thromboembolism in patients with cancer: a randomized controlled study.  Arch Intern Med. 2002;162(15):1729.

Bauer KA.  Treatment of venous thromboembolism in patients with malignancy.  Uptodate.  Accessed 4-28-13

Akl EA, et al.  Anticoagulation for the long term treatment of venous thromboembolism in patients with cancer. Cochrane Database Syst Rev. 2008;