Prophylaxis against venous thromboembolism in ambulatory patients with cancer.

Copyright © 2013 Massachusetts Medical Society. The risk of venous thromboembolism is four to seven times as high among patients with cancer as among persons without this disease.1,2 This risk is highest for patients with certain types of solid tumors and hematologic cancers and is increased for patients who are receiving chemotherapy or radiotherapy, who have undergone operative procedures, who have metastatic disease, or who have inherited thrombophilias. Studies have indicated that the mechanisms of this effect may include mucin production by tumors, exposure of tissue factor–rich surfaces and tissue factor–bearing microparticles, cysteine proteinase production leading to thrombin generation, and local hypoxia.3,4 Venous thromboembolism is the second leading cause of death in patients with cancer,5 and overall mortality is increased among patients who have both conditions. In one study, the 1-year survival rate among these patients was one third the survival rate among patients who had cancer but did not have venous thromboembolism.6 The incidence of cancer-associated thrombosis has increased,7-10 probably because of a combination of improved treatment outcomes resulting in longer patient survival, more aggressive and prothrombotic treatment regimens, an aging population, and increased detection owing to improvements in imaging technology and the frequency of imaging. Awareness of venous thromboembolism has increased considerably. As a result of the Surgeon General’s call to action in 2008 to prevent deep-vein thrombosis and pulmonary embolism, programs have been created to assess and evaluate the occurrence of this condition. The Institute of Medicine declared hospital-acquired venous thromboembolism a medical error. The Agency for Healthcare Research and Quality has stated that providing prophylaxis against venous thromboembolism is one of the most important measures that can be taken to improve patient safety. The usefulness of prophylaxis against venous thromboembolism after orthopedic joint-replacement surgery is not questioned, and therefore, the Centers for Medicare and Medicaid Services has declared it a hospital-acquired condition, with a negative effect on reimbursement. The use of prophylactic anticoagulation therapy in most hospitalized patients with cancer and in patients undergoing surgery for cancer has been endorsed despite limited data.11-13 Empirical prophylaxis against venous thromboembolism in ambulatory patients who have cancer remains controversial. The largest studies of prophylaxis against venous thromboembolism, the Prophylaxis of Thromboembolism during Chemotherapy (PROTECHT) trial14 and the SAVE-ONCO study,15 showed decreased rates of events among patients who were receiving chemotherapy for cancer. Smaller studies involving selected patients at higher risk for venous thromboembolism, such as those with pancreatic cancer, have shown a greater magnitude of decrease in venous thromboembolism with the use of prophylaxis.16,17 However, the effect of prophylaxis on morbidity, mortality, and cost has not been rigorously studied.