Dalteparin Thromboprophylaxis Associated With Reduced Risk of VTE in Cancer

ORLANDO ­– Thromboprophylaxis with dalteparin is associated with a non-significant decreased risk of venous thromboembolism (VTE) with no impact on major bleeding or survival but an increased risk of clinically relevant bleeding in ambulatory patients with cancer at high-risk for VTE.¹

“Recent randomized trials have shown that outpatient prophylaxis is safe, efficacious, and feasible but with low thromboembolic event rates,” Alok A. Khorana, MD, medical oncologist at Cleveland Clinic in Cleveland, OH, said during his presentation at the 57^th annual American Society of Hematology meeting. “A risk-adapted approach to thromboprophylaxis would optimize the risk-to-benefit ratio.”

Because ambulatory patients with cancer at high-risk for VTE (Khorana score ≥ 3) can be identified using a validated risk score using 5 patient characteristics, researchers sought to evaluate the benefit of outpatient dalteparin thromboprophylaxis in this population.

For the multicenter, controlled PHACS trial, researchers enrolled 117 patients with cancer at high-risk for VTE who were initiating a new systemic chemotherapy regimen. Of those, 98 were deemed to have a VTE on initial screening and were randomly assigned to receive dalteparin 5000 units daily subcutaneously or no prophylactic anticoagulation for 12 weeks. Nine percent of patients not randomized had baseline VTE. Participants were screened with lower extremity ultrasounds every 4 weeks during the study.

Results showed that VTE occurred in 12% of patients in the dalteparin arm and 21% in the control arm (HR, 0.69; 95% CI, 0.23 – 1.89), corresponding to an absolute risk reduction of 9% with dalteparin. Major bleeding occurred in 1 patient in each arm but clinically relevant bleeding occurred in 6 patients who received dalteparin compared with no patients in the control arm. Researchers observed no difference in overall survival between the 2 treatment arms.

“Dalteparin prophylaxis was associated with a high absolute risk reduction, but this was non-significant in this underpowered study,” Dr Khorana noted. “Dalteparin prophylaxis did not worsen major bleeding or mortality but did significantly increase clinically relevant non-major bleeding.”

The findings suggest that consideration should be given to screening high-risk patients in clinical practice prior to initiating systemic therapy.

“A Khorana score of ≥ 3 was successful in identifying patients with high rates of VTE,” Dr Khorana concluded. “Strong consideration should be given to routine screening of patients with a score ≥ 3 prior to initiating systemic therapy.”

Reference

1. Khorana AA, Francis CW, Kuderer NM, et al. Dalteparin thromboprophylaxis in cancer patients at high risk for venous thromboembolism: A randomized trial. Oral presentation at: 57^th American Society of Hematology (ASH) Annual Meeting & Exposition; December 5-8, 2015; Orlando, FL.