Risk of recurrent cancer-associated thrombosis after discontinuation of anticoagulant therapy.

Background: Clinical guidelines suggest continuing anticoagulation therapy for >6 months for patients with active cancer and venous thromboembolism (VTE). However, data regarding the safety of its discontinuation are scarce. Objectives: To valuate the risk factors and the incidence of recurrent VTE 6 months after the discontinuation of anticoagulation therapy in patients with cancer-associated thrombosis (CAT). Methods: We performed a retrospective study on consecutive patients with CAT recruited between 2008 and 2019. The primary and secondary outcomes were recurrent VTE at 6 and 12 months, respectively. Sensitivity analyses were conducted to investigate the possible heterogeneity of these effects. Results: A total of 311 patients were included, among whom 33.4% had metastases and 30.8% were still receiving oncological treatment after 6 months of anticoagulant therapy. At 6 and 12 months, the incidences of recurrent VTE were 6.1% (95% CI, 3.5-9.4%) and 8.7% (95% CI, 5.8-12.4%), respectively. Recurrent VTE was more frequent in patients with metastases at 6 (sub-distribution hazard ratio [SHR] 3.83; 95% CI, 1.54-9.52) and 12 months (SHR 5; 95% CI, 2.2-11.5). Patients with incidental VTE had fewer recurrent events at 6 (SHR 0.3; 95% CI, 0.1-0.8) and 12 months (SHR 0.3; 95% CI, 0.1-0.6) after discontinuing the anticoagulant therapy. Conclusion: The incidence of recurrent VTE at 6 and 12 months following the discontinuation of anticoagulant therapy is higher in patients with CAT. Patients with metastases were at an increased risk of recurrent VTE, whereas patients with incidental VTE were at a lower risk.