Antithrombotics in thrombosis and cancer.

Many cancer patients reportedly are in a hypercoaguable state, with recurrent thrombosis due to the impact of cancer cells and chemotherapy or radiotherapy on the coagulation cascade. Studies have demonstrated that unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH) interfere with various processes involved in tumor growth and metastasis. These include fibrin formation, binding of heparin to angiogenic growth factors such as basic fibroblast growth factor and vascular endothelial growth factor, modulation of tissue factor and, perhaps, other more important modulatory mechanisms such as enhanced tissue factor pathway inhibitor (TFPI) release and inhibition of various matrix-degrading enzymes. Clinical trials have suggested a clinically relevant effect of LMWH, compared with UFH on the survival of cancer patients with deep vein thrombosis. Similarly, the impact of warfarin on the survival of cancer patients with thromboembolic disorders was demonstrated. Studies from our laboratory demonstrated a significant role for LMWH, warfarin, anti-VIIa and LMWH-releasable TFPI on the regulation of angiogenesis, tumor growth, and tumor metastasis. Thus, modulation of tissue factor/VIIa noncoagulant activities by LMWH, warfarin, anti-VIIa or TFPI might be a useful therapeutic option for the inhibition of angiogenesis associated with human tumor growth and metastasis.