ABSTRACT
Venous thromboembolic disease (VTE), including deep venous thrombosis (DVT) and pulmonary
embolism (PE), is an underdiagnosed and underappreciated clinical problem in cancer
patients that results in significant patient morbidity and mortality. Standard treatment
practices, including the use of intravenous unfractionated heparin (UFH) for initial
anticoagulation, the use of oral warfarin for chronic anticoagulation, and the prescription
of only 3 to 6 months total therapy, may not be optimal in the setting of active cancer
and ongoing anticancer therapy. Challenges of VTE management in cancer patients include
heparin resistance because of excess circulating acute phase proteins, increased recurrence
rates during warfarin therapy (target international normalized ratio 2 to 3), limited
venous access to support therapeutic monitoring, and increased bleeding rates during
anticoagulation. Bleeding during anticoagulation is of particular concern in patients
with disease- or chemotherapy-related thrombocytopenia, central nervous system involvement
with cancer, and recent surgical intervention. Low-molecular-weight heparins (LMWHs)
have been shown to be equally effective and safe for initial anticoagulation compared
with UFH and have gained popularity, especially in the setting of VTE in cancer. LMWHs
have the advantage of less nonspecific protein binding, subcutaneous weight-based
dosing without the need for monitoring in most cases, and less heparin-induced thrombocytopenia.
Recent clinical trials have shown LMWHs are at least as effective as oral warfarin
for long-term anticoagulation in cancer patients. Interest in LMWHs and several new
classes of parenteral and oral anticoagulants extends beyond the primary and secondary
prevention of VTE and includes antiangiogenesis, metastasis prevention, and survival
prolongation.
KEYWORDS
Cancer - thrombosis - heparin - warfarin - hypercoagulability