Anticoagulant treatment and survival in cancer patients. The evidence from clinical studies

Hematology Service, University Clinic of Navarra, University of Navarra, Pamplona, Spain. rlecumber@unav.es

The association between cancer and an increased incidence of venous thromboembolism (Trousseau syndrome) is well characterized and recent studies have shown that the hemostatic system plays a key role at different stages in the process of tumorigenesis. Anticoagulant drugs therefore appear to be an attractive strategy in cancer therapy, with an effect that would surpass the benefit of preventing thrombosis. This hypothesis was initially supported by the post-hoc analysis of clinical trials not primarily designed to evaluate the effect of anticoagulants, mainly low molecular weight heparins (LMWH), on cancer survival. Other studies regarding the addition of unfractionated heparin or oral anticoagulants to standard cancer treatment offered controversial results. However, recent investigations among cancer patients without deep venous thrombosis, with cancer-related mortality as the primary end point, suggest that at least in some patients LMWH may exert an antineoplastic effect in vivo and alter the natural history of malignant disease by increasing the response rates and, therefore, improving survival. Additional research on this field is needed to clarify the biological mechanisms involved and to answer yet unsolved questions such as the types of tumor and stages of disease most suitable for this treatment as well as how to optimize treatment regimens.