Venous thromboembolism (VTE) in patients with cancer: epidemiology and risk factors.

Although cancer is recognized as a major risk factor for venous thromboembolism, the exact magnitude of the problem and specific risk factors most strongly associated with the development of VTE is not well defined. Several recent studies have shown that the incidence of VTE is highest in patients who present with metastatic cancer, particularly cancers associated with a high one-year mortality rate, such as pancreatic cancer. The incidence rate of VTE is highest in the first few months after the diagnosis of cancer, and it decreases over time thereafter. For most cancers, it is not clear to what extent undergoing major surgery adds to the already high risk of VTE associated with the presence of the cancer. However, patients with glioma clearly have a very high incidence of VTE soon after they undergo any invasive neurosurgical procedure. Active chemotherapy, the use of erythropoetin agents, and the use of certain anti-cancer therapies such as thalidomide, high-dose steroids, and anti-angiogenic therapy also increase the risk of thrombosis. Similar to patients without cancer, the risk of VTE is higher in patients with coexisting chronic medical illnesses. Development of VTE is clearly associated with decreased survival and this effect is greater among patients initially diagnosed with local or regional stage cancer compared to patients with metastatic cancer.