Thromboembolism associated with new anti-cancer treatment strategies in combination with conventional chemotherapy: new drugs, old risks?

Thrombosis is a frequent complication of cancer, and the presence of a tumour confers a prothrombotic state. Despite modern interventions, venous and (rarely) arterial thromboembolic disorders are still among the most common complications of cancer, and are a cause of substantial morbidity and mortality in these patients. The severity, number of complications, and recurrence rates of thromboembolic disease are also substantially greater. Recurrent thromboembolism is more likely to occur in patients with cancer as in healthy individuals, even when established on oral anticoagulant therapy, and these patients tend to need longer stays in hospital, respond less well to oral anticoagulant therapy, and have a poorer prognosis. Some cancers are more likely to be prothrombotic than others, but this feature is also influenced by disease staging, immobility, and being in hospital, as well as by interventions such as surgery or chemotherapy. What is less known are the thomboembolic risks associated with new treatment strategies for cancer. Two such strategies, the inhibition of angiogenesis and matrix metalloproteinases, are worthy of some further discussion.