ASCO Issues Guidelines for Preventing and Treating Venous Thromboembolism in Cancer Patients

November 6, 2007 — New guideline recommendations have been released for the use of anticoagulation in the prevention and treatment of venous thromboembolism (VTE) in patients with cancer. The guidelines, which were prepared by an international panel of researchers and are published in the October 29 Early Release Articles issue and will be published in the December 1 issue of the Journal of Clinical Oncology.
"Venous thromboembolism is an increasingly common cause of morbidity and mortality among cancer patients," said Gary H. Lyman, MD, director of the Health Services and Outcomes Research Program in Oncology at Duke University in Durham, North Carolina, and cochair of American Society of Clinical Oncology's (ASCO) Venous Thromboembolism Expert Panel. "The risk is particularly high among cancer patients who are hospitalized, undergoing surgery or receiving certain systemic therapies including chemotherapy, hormonal therapy and some of the new antiangiogenesis agents."
VTE is a major complication of cancer and occurs in 4% to 20% of patients. It is also one of the leading causes of mortality in patients with cancer, and for reasons that remain yet unclear, the burden of VTE seems to be increasing in this population. Patients with primary gastrointestinal tract, brain, lung, gynecologic, pancreatic, ovarian, renal, bladder, and hematologic cancers, as well as those with metastatic disease and a history of VTE, are also at a higher risk.
"In the absence of contraindications to anticoagulation, prophylactic anticoagulation should be considered for all hospitalized cancer patients including those undergoing surgery," Dr. Lyman told Medscape Oncology.
The panel members conducted an exhaustive systematic review of the literature of randomized clinical trials (RCTs) that examined the efficacy and safety of anticoagulants in patients with cancer, focusing on prevention of VTE, bleeding complications, and overall survival. Based on these studies, recommendations were developed to help prevent VTE in patients with cancer who are hospitalized, ambulatory, and undergoing surgical treatment.
Other organizations have created guidelines, such as those issued by the American College of Chest Physicians and the National Comprehensive Cancer Network. The American College of Chest Physicians has developed general guidelines on VTE treatment and developed a small section on cancer, whereas the National Comprehensive Cancer Network has recently come out with guidelines based on a panel consensus.
"I think it is safe to say that this is the first comprehensive effort," said Dr. Lyman. "The ASCO guidelines differ in that they are based on an exhaustive search and comprehensive summary of the world's literature and use that evidence to develop recommendations to address the major clinical issues related to thrombosis prevention and treatment that arise in oncology."
The ASCO panel was a mix of world-famous experts in thrombosis and methodology, he added, and the resulting guidelines underwent extensive internal and external review by other leading experts before further review by the ASCO board of directors and their own reviewers.
Their guideline recommendations included the following:
Patients with cancer who are hospitalized should be considered candidates for VTE prophylaxis with anticoagulants in the absence of bleeding or other contraindications to anticoagulation.
Routine prophylaxis with an antithrombotic agent is not recommended for ambulatory patients during systemic chemotherapy, but patients receiving thalidomide or lenalidomide with chemotherapy or dexamethasone are at high risk for thrombosis and warrant prophylaxis.
All patients undergoing major surgical intervention for malignant disease should be considered for thromboprophylaxis.
Low molecular weight heparin (LMWH) represents the preferred agent for both the initial and continuing treatment of patients with cancer who have established VTE.
The impact of anticoagulants on survival of patients with cancer requires additional study and cannot be recommended at present.
Patients with cancer should be encouraged to participate in clinical trials designed to evaluate anticoagulant therapy as an adjunct to standard anticancer therapies.
"There are very little data on the issue of thrombosis prevention in cancer patients," said Dr. Lyman. "However, the evidence that exists would suggest that the issue has received little attention by either patients or their providers."
A few surveys suggest that a low number of patients who are hospitalized received prophylactic anticoagulation as recommended by guidelines. Dr. Lyman also pointed out that although patients with established blood clots are generally treated appropriately, secondary prophylaxis to prevent recurrence varies greatly in method or duration.
"But there is also evidence that much more attention is being paid to these life-threatening complications in the medical literature and by the major organizations," he added.
Based on their evidence, patients with cancer who are being treated for established VTE should continue to take anticoagulation for up to 6 months or longer if they continue to receive treatment for active malignancy. "Risk models and other methods for identifying ambulatory cancer patients at increased risk for VTE are needed," Dr. Lyman said. "At the moment, we cannot recommend routine anticoagulation for all cancer patients, but it should be considered in patients with multiple myeloma receiving thalidomide or lenalidomide along with chemotherapy."
"Other novel agents may also warrant consideration for anticoagulation as more experience is gained," he pointed out.
The study authors have disclosed various financial relationships with Sanofi-Aventis, Pfizer, Eiasi Pharmaceuticals, GlaxoSmithKline, Bristol-Myers Squibb; Bayer, Boehringer-Ingelheim, Darichi, Takeda, Eisai Pharmaceuticals, and Pharmion.
J Clin Oncol. Published online October 29, 2007.