Patients with cancer are at increased risk for thrombosis, and those with thrombi have poorer overall survival rates than those without. In a new review article, Dr. Jean Connors from Brigham and Women’s Hospital and Dana Farber Cancer Institute summarizes available data and provides guidance for determining which patients might benefit from thromboprophylaxis.
The incidence of cancer-associated thrombosis is increasing, 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.
• What is the differential risk of venous thromboembolism among patients with cancer compared to patients without cancer?
The risk of venous thromboembolism is four to seven times as high among patients with cancer as among persons without this disease. This risk is highest among patients with certain types of solid tumors and hematologic cancers and is increased among patients who are receiving chemotherapy or radiotherapy, who are undergoing operative procedures, who have metastatic disease, or who have inherited thrombophilias.
• What are results in two recent trials of low-molecular-weight heparin preparations used for prophylaxis in cancer patients?
The PROTECHT [Prophylaxis of Thromboembolism during Chemotherapy] study randomly assigned 1150 ambulatory patients with cancer to receive prophylactic nadroparin or placebo. The nadroparin group, as compared with the placebo group, had a 50% reduction in composite venous and arterial events (2.0% vs. 3.9%, P=0.02). The SAVE-ONCO trial randomly assigned 3212 ambulatory patients receiving chemotherapy for locally advanced solid tumors or metastatic cancer to receive a prophylactic dose of semuloparin or placebo. The overall incidence of venous thromboembolism was 1.2% in the semuloparin group, as compared with 3.4% in the placebo group (hazard ratio, 0.36; 95% confidence interval, 0.21 to 0.60; P<0.001).
Morning Report Questions
Q: At what platelet threshold should anticoagulant therapy be held in patients with cancer receiving chemotherapy and prophylactic anticoagulation?
A: Ambulatory patients with cancer who are receiving chemotherapy and prophylaxis against venous thromboembolism can be more closely monitored, and anticoagulation therapy can be withheld if there are changes in renal function or the platelet count that suggest an increased risk of bleeding. All guidelines suggest withholding any dose of anticoagulation drug if the platelet count is less than 50,000 per cubic millimeter; however, for very high-risk patients, the continued use of prophylactic anticoagulation therapy can be considered if the platelet count is more than 30,000 per cubic millimeter.
Q: What are current guidelines on the use of prophylactic anticoagulation against venous thromboembolism in ambulatory patients with cancer?
A: Current guidelines from the American College of Chest Physicians (ACCP), the American Society of Clinical Oncology (ASCO), and the National Comprehensive Cancer Network (NCCN) have subtle differences, but all advise against the use of routine prophylaxis against venous thromboembolism in most ambulatory patients with cancer. An exception is made for patients with multiple myeloma who have received either multiagent chemotherapy or thalidomide-lenalidomide regimens that include dexamethasone; among these patients, rates of venous thromboembolism of 23 to 75% have been reported.