Clinical outcomes of half-dose extended anticoagulation in cancer-associated pulmonary thromboembolism: a real-world cohort study

Background Current guidelines recommend extended anticoagulation for cancer-associated pulmonary thromboembolism (CAPE) in patients with active cancer. However, maintaining a full-dose regimen over an extended period raises concerns regarding increased bleeding risk and potential drug interactions with anticancer therapy. Furthermore, the optimal duration of anticoagulation beyond the initial treatment phase remains insufficiently explored. Purpose This study aims to evaluate the impact of reduced-dose anticoagulation following an initial six-month treatment period on CAPE-related clinical outcomes. Methods Of 3,170 patients diagnosed with CAPE between January 2013 and December 2021, 858 were included after excluding those with follow-up <3 months, insufficient initial treatment, or inconclusive relation between cancer and PE. Clinical and demographic data were retrieved from electronic medical records, including details on anticoagulation type, dose, and duration. The primary outcome was recurrent PE or deep vein thrombosis (DVT), while the primary safety outcome was major and/or minor bleeding, defined according to the International Society on Thrombosis and Hemostasis criteria. Results The mean age of the patients was 65 years [56.0–72.0], with 47.8% being male. Over a median follow-up of 33.4 months [17.6–53.0], PE/DVT recurred in 172 patients, with a Kaplan-Meier estimated 3-year recurrence rate of 20.2%. In multivariate analysis, symptomatic PE, impaired renal function, advanced cancer status, and progressive disease despite anticancer treatment were associated with a higher risk of PE/DVT recurrence (all p < 0.05) (Figure 1). A longer duration of anticoagulation was independently linked to a lower recurrence risk (adjusted HR 0.982, 95% CI [0.967–0.998], p = 0.028). Extended anticoagulation with a half-dose regimen after six months of initial treatment showed no significant difference in PE/DVT recurrence or anticoagulation-related major bleeding events compared to full-dose anticoagulation (recurrence: HR 0.621, 95% CI [0.317–1.215], p = 0.164; bleeding: HR 0.772, 95% CI [0.253–2.354], p = 0.650) (Figure 2). Conclusion In patients with CAPE, prolonged anticoagulation was associated with a lower risk of recurrent PE/DVT. A reduced-dose strategy may offer a safe and effective alternative for extended anticoagulation. Future prospective trials are needed to refine anticoagulation strategies through tailored risk stratification in CAPE patients.