Which cancer patients need prophylaxis for DVT and pulmonary embolism?
People with cancer have the highest rates of deep venous thrombosis (DVT) and pulmonary embolism (PE). However, the risk of venous thromboembolism varies widely by cancer type and between patients. Daily anticoagulant use can reduce the risk of DVT and pulmonary embolism, but at a cost of increased bleeding risk, patient inconvenience and discomfort, and cost. Which cancer patients should receive anticoagulant prophylaxis against venous thromboembolism?
Risk of DVT and PE in Cancer Patients
As many as 10% of patients with cancer will develop clinically diagnosed venous thromboembolism (DVT or PE), a rate at least 6 times that of people without cancer. The cancer type is a major contributor to risk for DVT and PE:
Brain cancer, multiple myeloma, pancreatic and gastric cancer have the highest risk for DVT and pulmonary embolism (~40% for patients with pancreatic cancer).
Lung cancer, lymphoma, and non-prostate GU and gynecologic cancers all carry high risk for DVT and PE.
Most other cancers (prostate, colon, breast) are considered together at increased risk for DVT/PE, but less so than the above (at least at early stages).
Almost any advanced-stage or metastatic cancer may cause a venous thrombotic event.
Multiple myeloma patients receiving thalidomide or lenalidomide treatment are at the highest risk of all (up to 75% in some series).
Although the risk is higher for DVT or PE during hospitalization with cancer (owing to acute illness and immobility), the large majority of venous thromboembolism events happen to people with cancer outside the hospital (since this population is vastly larger). The Khorana score (click for online calculator) is a well-validated tool that can be used to calculate risk for DVT and pulmonary embolism in patients with cancer. A score of ≥3 is the highest risk category, with a 7% chance of DVT / PE within 2.5 months (median). The Khorana score should not be used for brain cancer or myeloma.
Prophylaxis for DVT and PE in Inpatients with Cancer
Most hospitalized patients receive chemoprophylaxis against venous thromboembolism, although it probably makes little if any difference in clinical outcomes for hospitalized patients at ordinary risk for DVT and PE. The largest randomized trial showed no meaningful benefit of enoxaparin prophylaxis in hospitalized patients overall. In patients with cancer who are hospitalized, on the other hand, the risk of DVT and PE are markedly elevated. Experts advise anticoagulation prophylaxis for almost all such patients who are not at high bleeding risk. Randomized trials have demonstrated a reduction in DVT / PE risk among high risk patients receiving chemoprophylaxis (including cancer patients) -- although no mortality reduction has been demonstrated. Experts also recommend pharmacologic DVT-PE prophylaxis (i.e., heparin) for cancer patients prior to and after surgery.
Should Outpatients with Cancer Receive DVT-PE Prophylaxis?
Whether ambulatory patients with cancer should receive routine anticoagulation prophylaxis against venous thromboembolism is much more controversial. Guidelines from major specialty societies (ASCO, ACCP, NCCN) advise against routinely providing anticoagulation to prevent DVT and pulmonary embolism in patients with cancer outside the hospital. However, for ambulatory patients with multiple myeloma being treated with thalidomide or lenalidomide-based chemotherapy, most experts advise the use of anticoagulation (such as 40 mg of enoxaparin daily or warfarin to a target INR range of 1.5 to 3) to prevent DVT and PE. The professional societies also advise consideration of anticoagulation prophylaxis for ambulatory cancer patients at high risk for DVT and pulmonary embolism, such as those with a Khorana score ≥3. The ACCP suggests prophylaxis with heparin (low-molecular weight or unfractionated) for cancer patients at high DVT risk, while ASCO and NCCN recommend discussion of the risks and benefits of prophylaxis between doctors and patients. Read More: American Society of Clinical Oncology Guidelines (2013 Practice Update) American College of Chest Physicians 2012 Guidelines National Comprehensive Cancer Network Guidelines Barsam SJ et al. Anticoagulation for prevention and treatment of cancer-related venous thromboembolism. Br J Haematol. 2013 Jun;161(6):764-77.
Jean M. Connors. Prophylaxis against Venous Thromboembolism in Ambulatory Patients with Cancer. NEJM June 26 2014.
More on the Khorana score (Cleveland Clinic)