Tumor vasculogenic mimicry formation as an unfavorable prognostic indicator in patients with breast cancer

Vasculogenic mimicry (VM), a newly defined pattern of tumor blood perfusion, describes the functional plasticity of aggressive tumor cells forming de novo vascular networks and is associated with the cancer progression and metastasis. However, the VM-positive rate and the impact of VM status on breast cancer patients' clinicopathological parameters and prognosis remain unclear. Thus, we performed a meta-analysis by incorporating all available evidence to clarify these issues. Eight studies that involved 1,238 breast cancer patients were eligible for inclusion in our study. We found the VM-positive rate was 24% (pooled proportion was 0.24, 95% CI=0.13-0.34), and VM was significantly associated with larger tumor size (> 2 cm) (OR=0.49, 95% CI=0.26-0.90, P=0.02) and lymph node metastasis (OR=0.27, 95% CI=0.13-0.57, P=0.0005). A boardline correlation was also identified between VM and poorer differentiation (Grade II-III) (OR=0.07, 95% CI=0.00-1.24, P=0.07). Nevertheless, no statistically significant associations were observed between VM and hormone receptor and human epidermal growth factor receptor 2 status. Moreover, the results showed that breast cancer patients with VM-positive have a shorter overall survival than those with VM-negative (HR=0.23, 95% CI=0.08-0.38, P=0.003). In summary, VM was associated with more aggressive tumor phenotype and poor prognosis in patients with breast cancer. Developing strategies against the VM formation would be a promising therapeutic approach to breast cancer.