Intratumoral tissue factor expression and risk of venous thromboembolism in brain tumor patients

Background: Brain tumor patients have an increased risk of venous thromboembolism (VTE). An important role in cancer-related VTE has been suggested for tissue factor (TF), the main initiator of the coagulation cascade. We conducted a prospective cohort study to determine whether expression levels of TF in brain tumors are associated with future VTE.

Patients and methods: We immunohistochemically determined TF-expression in brain tumor specimens of 96 adult patients (8 low-grade and 82 high-grade gliomas, 6 embryonal tumors) that were included in the Vienna Cancer and Thrombosis Study (CATS). Each patient was prospectively followed until the occurrence of VTE and/or death within a period of two years or loss of follow-up.

Results: Fifteen brain tumor patients (15.6%) developed VTE during follow-up. Seventy-seven brain tumors (80.2%) stained positive for TF. Staining was strong in 13 (13.5%), moderate in 64 (66.7%) and negative in 19 (19.8%) tumors. No statistically significant association between TF-expression (negative, focal, widespread) and the occurrence of VTE was found. The hazard ratio (HR) for VTE was 1.30 (95% confidence interval [CI]: 054 - 3.14, p=0.567) when patients with negative-, focal- and widespread TF expression were compared and not statistically significant. Also when tumors were categorized into two groups (focal/widespread versus negative TF-expression), the HR for future VTE was not statistically significant (HR: 1.45, 95% CI: 0.44 - 7.37; p=0.578). An association can still not be definitely excluded, as this study was underpowered.

Conclusions: Our data indicate that TF-expression levels in brain tumors are not strongly associated with future VTE.