Heparins in cancer-associated venous thrombosis

A close causal relationship between cancer and venous thrombosis gives rise to questions about the effect of treatment modalities, in particular of the administered drugs, in patients with cancer-related venous thrombosis. An increased risk of chemotherapy-associated venous thromboembolism (VTE) has been well documented, while the effect of heparins used in VTE treatment on the disease course and prognosis in cancer patients has not been fully elucidated. This paper discusses the outcomes of the studies conducted so far investigating the role of heparins, in particular, low-molecular-weight heparins (LMWHs), in the prevention of thrombosis in cancer patients. It also focuses on such aspects of the treatment for cancer-associated VTE as treatment duration and drugs used. The paper summarizes the often discrepant results of long-term therapies with various LMWH products, emphasising that in this specific case the class effect is rather unlikely. It also presents the possible effects of heparins administered as part of cancer treatment, and points to the effects of LMWHs on cancer that are not related to an antithrombotic effect. On the 100th anniversary of heparin discovery, it can be said that heparin is irreversibly connected with thrombosis in the course of cancer.