Objective: To assess the effect of bevacizumab on tumor vessels, and the reversibility of the
effect, using contrast-enhanced ultrasonography (CEUS) and histology in patients with
metastatic liver tumors derived from colorectal cancer.
Background Data: Direct evidence on the reversibility of any change in tumor vascularity upon
bevacizumab cessation in the clinical setting is lacking.
Methods: The study included 10 patients who received chemotherapy including bevacizumab,
experienced a reduction in tumor vascularity as demonstrated by CEUS and consequently
underwent liver resection. CEUS was performed before and immediately after 4 courses of
chemotherapy and one day before surgery. The number of microvessels highlighted by anti-CD34
antibody in the viable tumor tissue was counted to quantify the microvessel density (MVD). As
a control, 10 surgical specimens from 10 patients who had not received chemotherapy were