Relevance of recurrent venous thromboembolism according to location of metastasis in patients with cancer-associated thrombosis. A cohort study

Background: Risk of VTE recurrence (VTEr) in patients with cancer-associated thrombosis (CAT) is high. Cancer-related risk factors for VTEr have been studied, but information about the importance of location of metastasis is scarce.

Objectives: 1) Evaluate rate of VTEr in CAT patients according to location of metastasis, and 2) Identify variables associated to VTEr during long-term follow-up.

Methods: A retrospective, single-center, non-interventional study of consecutives patients with CAT conducted between 2007 and 2022. Haematological neoplasms were excluded.

Results: Among 1248 patients with CAT (age 64.1 ± 12.8 years; 48.2 % female) followed-up for 13.19 months (p25-75, 5.6-26.9) there were 141 VTEr. The rate of VTE recurrence in patients without and with metastasis were 4.72 per 100 patient-years (95%CI: 3.66-6) and 10.05 per 100 patient-years (95 % CI: 7.89-12.61), respectively. The metastases locations associated with VTEr, compared to those without metastasis, were lung (rate ratio [RR]: 2.21; 95 % CI: 1.42-3.43), liver (RR: 2.02; 95%CI: 1.26-3.24), pancreas (RR: 6.21; 95 % CI: 1.52-25.35), pleura (RR: 2.93; 95%CI: 1.58-5.41), bone (RR: 2.16; 95 % CI: 1.29-3.64) and adrenal (RR: 6.18; 95%CI: 2.97-12.86). Multivariate analysis of variables associated with VTEr beyond 12 months were male sex (hazard ratio [HR] 1.54, 95%CI: 1.08-2.19), ECOG performance status >1 (HR 1.74, 95%CI: 1.03-2.94), metastasis in 1-2 locations (HR 2.38, 95%CI: 1.68-3.37) and metastasis in >2 locations (HR 3.88, 95%CI: 1.68-8.98).

Conclusions: The rate of VTEr differs according to the location of metastasis. We identified variables related to VTEr during long-term follow-up which may help clinicians decide whether to continue anticoagulation.