Zosia Chustecka

October 10, 2012

October 10, 2012 (Vienna, Austria) — Cancer patients receiving chemotherapy are known to be at increased risk for venous thromboembolism (VTE), but the magnitude of the risk appears to differ by cancer type.

A study presented here at the 2012 European Society for Medical Oncology (ESMO) Congress set out to quantify the risk and estimate treatment costs for 2 common types of cancer: breast and prostate.

This study is a "real-world analysis," said lead author Nicole Kuderer, MD, from Duke University, Durham, North Carolina. Working with researchers from Sanofi, the team analyzed data on 34,114 patients in the United States with breast or prostate cancer collected in the IMPACT insurance claims database.

For patients with prostate cancer, the risk for VTE was 3.6% 3.5 months after the initiation of chemotherapy. Of the VTE events that occurred the first 3.5 months, 16.2% were pulmonary embolism events, 70.2% were deep vein thrombosis events, and 13.6% were both. After 12 months, the risk for VTE had increased to 8.1%.

For patients with breast cancer, the risk for VTE was similar; 3.9% 3.5 months after the initiation of chemotherapy, increasing to 7.1% after 12 months. The pattern of events at 3.5 months was also similar, with 12.4% presenting with pulmonary embolism, 78.1% with deep vein thrombosis, and 9.6% with both.

After 1 year, the healthcare costs (inpatient and outpatient) for patients who had suffered a VTE were substantially higher than for those who had not, Dr. Kuderer reported.

The VTE-related costs were $8,498.60 ± 20,034 for patients with prostate cancer and $7,744.48 ± 16,882 for patients with breast cancer.

"The risk of VTE at 3.5 months following chemotherapy initiation is about 4% in these 2 common cancer types, with the cumulative risk almost doubling at 12 months," Dr. Kuderer reported. "VTE development is associated with a significant economic burden in terms of healthcare expenditure."

What to do about this remains a topic for further research, Dr. Kuderer told Medscape Medical News. There is not enough evidence to recommend that all cancer patients receiving chemotherapy also receive routine prophylactic anticoagulation to prevent the VTE events that occur in a few patients, she said. There is a balance between the benefit of prophylaxis and potential harm (such as the increased risk of bleeding with anticoagulants), and cancer patients are already at an increased risk for VTE, she explained.

There is intense work going on to identify patients who are at higher risk for VTE, in whom prophylaxis would have a higher benefit to risk ratio, she continued.

One such study, sponsored by the National Institute of Health (NIH), is using a clinical risk score (which Dr. Kuderer helped develop [Blood. 2008;111:4902-4907]) to identify cancer patients at high risk for VTE. Patients are being randomized to receive low-molecular-weight heparin or a control drug, and then followed with ultrasound and computed tomography to identify VTE. Dr. Kuderer is hopeful that this large NIH study will provide some answers to the long-standing question of how to identify patients who are at the highest risk and who would benefit from thromboprophylaxis.

In the meantime, this issue is often left to the discretion of the oncologist. During a debate on the use of thromboprophylaxis in ambulatory cancer patients on chemotherapy that took place during the meeting, Mario Mandalà, MD, from the Department of Oncology and Hematology at Ospedali Riuniti in Bergamo, Italy, emphasized that current guidelines recommend against routine use.

However, all the guidelines also make some exceptions to this rule, he noted.

The ESMO guidelines on venous thromboembolism in cancer patients (Ann Oncol. 2010;21[suppl 5]:v274-v276) recommend against routine use in ambulatory cancer patients on chemotherapy, but add that it should be "considered in high-risk patients," said Dr. Mandalà, who was involved in the development of those guidelines. Similar wording is found in the guidelines from the American College of Chest Physicians (Chest 2012;133[6 suppl]:381S-453S).

Two other sets of guidelines actually single out a particular set of patients: those with myeloma treated with lenalidomide and thalidomide. Both the American Society of Clinical Oncology and the National Comprehensive Cancer Network guidelines mention myeloma patients as the exception to the recommendation against routine thromboprophylaxis, he said.

Dr. Mandalà concluded that there might be some high-risk patients who could benefit from thromboprophylaxis. He hopes that "ongoing studies will improve the predictability of risk," but in the meantime he urges his fellow clinicians to "follow the guidelines."

2012 European Society for Medical Oncology (ESMO) Congress: Abstract 1371P_PR. Presented October 1, 2012.