Anticoagulation Practice in Patients with Cancer-Associated Thrombosis: Insights from GeCAT, a German Prospective Registry Study.

Introduction: Cancer-associated venous thrombosis (CAT) is a common and serious complication of active malignancies, increasing in frequency during systemic treatment and radiotherapy. Due to a high risk of recurrence and bleeding, the administration of anticoagulants for initial treatment and secondary prevention of CAT is challenging. We conducted a prospective registry study of patients with acute CAT to evaluate the way treatment is given to these patients in routine practice.

Methods: From May 2015 to May 2017, all consecutive patients with acute venous thromboembolism (VTE) admitted to specialty or emergency departments of the participating hospitals in Berlin, Germany, were entered into the registry. Patients with cancer underwent extensive baseline evaluation including the type and location of thrombosis and use of anticoagulant therapy. Follow-up assessments were made at discharge and by telephone interviews at 3 and 6 months.

Results: A total of 382 patients with acute CAT were enrolled in the study, representing 24.5% of all patients with thrombosis. 70.4% of CAT patients had deep vein thromboses (DVT), 48.2% had pulmonary embolism (PE), and 18.6% had concurrent PE and DVT. A significant proportion of VTE (27%) was asymptomatic and was diagnosed only incidentally. At baseline, 97.9% of the patients received anticoagulant therapy, predominantly with low-molecular-weight heparin (LMWH) (n = 334, 87.4%). Direct oral anticoagulants (DOACs) were given to 5.8% of patients, and vitamin K antagonists were rarely used (<2% of patients). Changes in the prescription of antithrombotic agents were seen at discharge from hospital and during follow-up. Overall, the use of LMWH declined during follow-up, while the proportion of patients treated with DOACs increased to 32.4% at 6 months. At baseline, the most frequently used LMWH were enoxaparin and nadroparin, but many patients were switched to once daily tinzaparin prior to discharge. Initially and after discharge, the majority of patients were treated by oncologists. Overall, 263 (68.8%) and 222 (58.1%) patients were still alive and could be contacted at 3 and 6 months of follow-up, respectively. Of these, 84.0% and 71.6% were still on anticoagulant therapy (58.6% and 36.5% on LMWH).

Conclusion: In accordance with the guidelines, the majority of CAT patients received anticoagulation therapy for the recommended minimum duration of 3-6 months. LMWH remained the preferred option throughout the study, demonstrating good patient adherence. In deviation from guideline recommendations and available study results during the study period, more than a quarter of CAT patients were treated with DOACs. Only recently, DOACs have been established as another option for anticoagulation in CAT patients.