TREATMENT OF CANCER ASSOCIATED THROMBOSIS

Two studies presented at the 57th American Society of Hematology (ASH) Annual Meeting examine the common problem of cancer-associated thrombosis. One looked to validate dosing guidelines for avoiding chemotherapy-induced thrombocytopenia, a common autoimmune response to therapy; the second compared self-injection with a pill for the long-term treatment of cancer-associated thrombosis.

Chemotherapy-Induced Thrombocytopenia

In the first study, research results presented by Miao et al provided guidance for anticoagulation management in the setting of thrombocytopenia in cancer patients (Abstract 429).

Cancer patients commonly develop thrombosis and are often prescribed therapeutic anticoagulants while on chemotherapy. Thrombocytopenia is a common adverse event associated with chemotherapy. Patients with chemotherapy-induced thrombocytopenia have an increased risk of bleeding.

Managing anticoagulation in cancer patients who have chemotherapy-induced thrombocytopenia is challenging because clinicians must find a balance between the risks of both bleeding and recurrent thrombosis.

The current standard of care for preventing blood clots in a cancer setting includes treatment with low–molecular-weight heparin. However, there is limited evidence to support proper dosing to treat these episodes in the setting of chemotherapy-induced thrombocytopenia. In 2010, Memorial Sloan Kettering Cancer Center implemented guidelines for low–molecular-weight heparin dose modifications in the setting of thrombocytopenia.

To evaluate the safety and efficacy of these guidelines, researchers conducted a retrospective analysis to evaluate the outcomes of cancer patients who were thrombocytopenic for at least 7 days and received a therapeutic dose of low–molecular-weight heparin from 2011 to 2013.

Investigators identified 102 patients with a collective 143 episodes of thrombocytopenia. The low–molecular-weight heparin dose was modified in 136 of the 144 episodes (95%), which showed adherence to the institutional guidelines.

Low–molecular-weight heparin doses were reduced in 20 episodes, withheld in 89 episodes, and managed with a combination of reduced or withheld doses in 27 episodes. In general, the more severe thrombocytopenic episodes were managed with holding low–molecular-weight heparin as opposed to dose reduction.

None of the patients experienced recurrent thrombosis or major bleeds when the anticoagulant management guidelines were followed.

The data support the safety and efficacy of following the Memorial Sloan Kettering guidelines for therapeutic low–molecular-weight heparin dose modification, balancing the dual risks of recurrent thrombosis and potential bleeding during periods of chemotherapy-induced thrombocytopenia in cancer patients. More research is needed to see whether a similar strategy would be appropriate for other oral anticoagulants.

Cancer-Associated Thrombosis

A study presented by Chai-Adisakopha et al suggests warfarin is acceptable for long-term treatment of cancer-associated thrombosis (Abstract 430).  

The standard treatment for cancer patients who develop blood clots is 3 to 6 months of anticoagulant therapy with low–molecular-weight heparin. However, there are few data to support the best ongoing anticlotting therapy beyond 6 months.  

This study evaluated the records of 1,502 patients with cancer-associated thrombosis. Investigators selected patients who had completed treatment with low–molecular-weight heparin for 6 months and divided them into two groups—One group of 763 patients continued to receive low–molecular-weight heparin, and the other group of 739 patients was switched to warfarin. Because low–molecular-weight heparin requires self-injections, warfarin is often thought to be preferred because it can be taken in pill form.

The cumulative incidence of major bleeding was 2.6% in the low–molecular-weight heparin group and 2.7% in the warfarin group. The cumulative incidence of total bleeding was 6.7% in the low–molecular-weight heparin group and 7% in the warfarin group.

The study found that switching to warfarin is not associated with an increase in recurrent venous thromboembolism, major bleeding, or total bleeding when compared with continuing low–molecular-weight heparin. Researchers concluded that warfarin is an acceptable alternative for low–molecular-weight heparin for patients with cancer-associated thrombosis.