Background: Patients with cancer-associated venous thromboembolism (VTE) are recommended to receive treatment with therapeutic anticoagulation for at least 3-6 months. Little data exist on extended treatment beyond 6 months.
Objective: To comprehensively summarize the best available evidence on incidence of recurrent VTE and major bleeding 6-12 months after the index event in patients with cancer-associated VTE.
Patients/methods: We systematically screened biomedical databases (MEDLINE, Embase, CENTRAL) to identify studies reporting recurrent VTE and/or bleeding events between 6 and 12 months after a diagnosis of cancer-associated VTE. Based on the observed heterogeneity in study design, setting, patient cohort characteristics, anticoagulation strategies, and outcome rates, no overall quantitative estimate of outcome rates was calculated.
Results: We screened 2597 publications and identified 11 eligible studies matching predefined in-/exclusion criteria, reporting on 3019 patients specifically during the 6- to 12-month period post-index VTE. Overall rates of recurrent VTE in this timeframe varied substantially (1%-12%), with the highest risk observed in the patient subgroup with residual vein thrombosis present at 6 months randomized to receive no anticoagulation (13%-15%). Reported rates of major bleeding between 6 and 12 months were between 2% and 5%.
Conclusions: In this systematic review, we provide a comprehensive and structured summary of the best available evidence on recurrence and bleeding risk between 6 and 12 months after cancer-associated VTE. VTE recurrence remains common beyond 6 months and continuation of different anticoagulation strategies has an acceptable safety profile indicated by lower bleeding rates. These findings support guideline recommendations to continue anticoagulation treatment beyond 6 months in patients with active cancer.
Keywords: anticoagulants; hemorrhage; neoplasms; venous thromboembolism; venous thrombosis.
© 2021 The Authors. Journal of Thrombosis and Haemostasis published by Wiley Periodicals LLC on behalf of International Society on Thrombosis and Haemostasis.