Prophylactic anticoagulation guidelines developed specifically for patients with cancer

Ambulatory patients with cancer who are undergoing chemotherapy should not receive prophylactic anticoagulation to prevent venous thromboembolism, according to new guidelines developed by the American Society of Clinical Oncology (ASCO) and presented at the 2008 ASCO Annual Meeting, Chicago. "It's not cost effective and we also do not recommend screening these patients for thrombophilia," said Mark Levine, MD, McMaster University, Hamilton, Ontario, Canada.

However, ASCO does recommend prophylactic anticoagulation for patients with myeloma who are receiving thalidomide plus chemotherapy or dexamethasone. Literature reports have indicated that the risk of venous thromboembolism in patients taking thalidomide plus dexamethasone ranges from 17% to 26%; the risk with thalidomide combined with other chemotherapeutic agents ranges from 12% to 28%. These patients are at high risk for thrombosis and warrant prophylaxis; until randomized clinical trial results focusing on this patient population are available, low-molecular-weight heparin or adjusted-dose warfarin treatment should be prescribed.

One recent study of patients with myeloma that included 234 patients receiving chemotherapy plus thalidomide or dexamethasone and 232 patients receiving dexamethasone alone demonstrated that pulmonary embolism occurred in 6.8% of patients receiving the combination treatment versus 1.7% of patients receiving dexamethasone. Deep vein thrombosis occurred in 11.5% and 1.7% of patients, respectively, Dr. Levine reported. "More research is needed to evaluate antithrombotic agents in patients with multiple myeloma receiving thalidomide or the thalidomide derivative, lenalidomide, plus chemotherapy," Dr Levine said. Other currently available studies are flawed because they are observational and uncontrolled, he said.

Additionally, more research is urgently needed to identify biomarkers present in ambulatory patients with cancer that would help predict an individual's likelihood of developing venous thromboembolism.

The new ASCO recommendations for prophylactic anticoagulation address other cancer populations, as well. Hospitalized patients with cancer should be considered candidates for prophylactic anticoagulation as long as there is no bleeding or other contraindication. All patients undergoing major surgery for malignant disease should be considered for thromboprophylaxis. Patients undergoing laparotomy, laparoscopy, or thoracotomy lasting >30 minutes should receive either low-dose unfractionated heparin or low-molecular-weight heparin; treatment should begin preoperatively or as early as possible in the postoperative period. Although mechanical anticoagulation measures such as compression should not be used alone, they may improve the efficacy of pharmacologic anticoagulation.

For patients with cancer and with established venous thromboembolism, the preferred treatment is low-molecular-weight heparin for 5 to 10 days; when long-term anticoagulation is indicated, therapy should last for 6 months. Indefinite anticoagulation can be considered for certain patients with active cancer.