Low molecular weight heparins in cancer

Management and prevention of venous thromboembolism (VTE) in cancer patients is challenging. Not only is the risk of VTE in cancer patients elevated compared to patients without malignancies, but also is standard treatment based on Vitamin K antagonists (VKAs) less effective and associated with an increased frequency of major bleeding. Therapy with Low Molecular Weight Heparin (LMWH) is less sensitive to drug interactions, not hindered by a narrow therapeutic window and needs no monitoring. LMWH therapy therefore seems more practical and may also be more effective in cancer patients. Moreover a possible survival benefit has been suggested, the underlying mechanism of which is not yet unraveled. A combination of cancer and thrombosis is a predictor of poor long-term survival. Anticoagulant drugs, especially LMWH, may be of influence on tumor progression. Hypercoagulability in cancer patients may indicate an aggressive change in the tumor and is associated with tumor progression. Hypercoagulability could on the other hand also be a risk factor for developing cancer. To assist clinicians in defining the role of LMWH in cancer patients, we categorized, summarized and critically weighed all available evidence on the subject. Based on available data derived from clinical trials recommendations on the application of heparin in oncological patients are made. However, many uncertainties remain regarding the subject of cancer related thrombosis in view of treatment and the possible effects on tumor biology by heparins.