Considerations and challenges with existing treatments for thrombosis in cancer patients.

PURPOSE

One of the standard treatments for cancer-associated thrombosis has been initial therapy with unfractionated heparin (UFH) followed by long-term therapy with an oral anticoagulant (i.e., warfarin). However, characteristics associated with these two agents may make them suboptimal for many cancer patients. This article will explore some of the considerations and limitations when using UFH and warfarin in the cancer population and will also utilize case studies to emphasize the importance of individualized care.

SUMMARY

UFH is an effective anticoagulant when doses are adjusted to maintain the activated partial thromboplastin time (aPTT) within a specified therapeutic range. However, due to the complex pharmacokinetics of this agent, patients must undergo frequent monitoring to maintain a therapeutic aPTT. In addition, UFH can be associated with serious adverse events including osteoporosis, heparin-induced thrombocytopenia, and bleeding. Similar to UFH, warfarin requires frequent monitoring and dose adjustments to maintain the International Normalized Ratio (INR) within the therapeutic range of 2.0 to 3.0. Warfarin also has numerous drug-herbal, drug-food, and drug-drug interactions, including interactions with many commonly used anti-tumor therapies. Complications related to UFH and warfarin in the treatment of cancer-associated thrombosis have gradually been minimized with the increased use of low molecular weight heparins (LMWHs), which are associated with reduced incidence of bleeding, heparin-induced thrombocytopenia, and drug interactions. In addition, LMWHs allow for convenient daily dosing without requiring routine monitoring and the option of home therapy.

CONCLUSION

When deciding on the optimal anticoagulant strategy, pharmacists must take into account the unique characteristics and needs of each individual patient as well as the specifics of the various anticoagulant therapies. Future strategies for the initial and long-term treatment of cancer-associated thrombosis may increasingly incorporate LMWHs because of factors related to safety and convenience.