ABSTRACT
Several steps in cancer progression were found on which heparin could have an effect, such as cancer-cell proliferation, activity of the host immune system, angiogenesis, migration of cancer and endothelial cells, invasion of cancer and endothelial cells, and adhesion of cancer cells to vascular endothelium. In fact, experimental studies have found that UFH exerts a variety of positive and negative effects on cancer progression. Because of the complex interaction between cancer and UFH and the existence of both enhancing and inhibiting effects, the overall effect in man is difficult to predict. Possibly, the balance of effects is different in various types of cancer. The effects of UFH and LMWH are often similar, but sometimes they are contradictory. For instance, UFH and highmolecular-weight heparin appear to enhance the binding of angiogenic growth factors to their receptors, whereas LMWH inhibits this binding.23 Moreover, studies have shown that UFH and LMWH can also influence the structure of the fibrin matrices, resulting in stimulatory and inhibitory effects, respectively, on in vitro angiogenesis.24
