By Gary Whitman, Professor, Diagnostic Radiology
Bevacizumab is an angiogenesis inhibitor, a therapy designed to inhibit the formation of new blood vessels. The rationale for the use of angiogenesis inhibitors like bevacizumab is based on the understanding that tumor cells require a constant blood supply to receive oxygen and nutrients.
The RIBBON 2 study showed that adding bevacizumab to chemotherapeutic agents for the treatment of HER2 negative metastatic breast cancer led to a significant increase in overall survival. The AVADO study demonstrated that adding bevacizumab to docetaxel resulted in a significant increase in progression-free survival in patients with metastatic breast cancer, without affecting toxicity. These results lead one to ask if bevacizumab should be given throughout the course of treatment in patients with metastatic breast cancer.
In addition, we should consider using MRI to monitor response and angiogenesis inhibition in patients receiving bevacizumab therapy. While MRI may be limited in analyzing small volumes of residual disease (such as small cell clusters), MRI can assess tumor perfusion and vascular leakiness in patients with residual disease.
Furthermore, we have the tools to extract parameters from the MRI dynamic contrast enhancement curves and correlate those parameters with evidence of response to therapy.