The cardiac risks of bevacizumab treatment in combination with chemotherapy

This study investigated the effects of bevacizumab (avastin) in combination with chemotherapy on the risk of cardiac related events, such as heart failure and cardiac related death.

Bevacizumab is a drug which targets a protein called vascular endothelial growth factor A (VEGF-A).  By binding to VEGF-A bevacizumab prevents formation of new blood vessels, and as a result the growth and spread of tumors is inhibited. Clinical studies have shown that treating colorectal cancers with bevacizumab alongside standard chemotherapy may increase progression free and disease free times (the time between the end of treatment and until the disease advances, or returns), as well as overall survival.

However, since bevacizumab interferes with the normal ability to form new blood vessels, an increased risk of diseases such as high blood pressure, heart failure and heart attacks if of concern. In this trial, whether bevacizumab increased the risk of arterial thromboembolic events (blockage of the arteries in the heart), cardiomyopathy (deterioration of the heart muscle), heart failure (failure of the heart muscle to efficiently pump blood) and cardiac related death (death directly related to heart disease) was examined.

The study included 6803 individuals over the age of 65, diagnosed with colorectal cancer, and who received chemotherapy. Of these 2787 patients were treated with bevacizumab in addition to chemotherapy and the remaining 4016 received chemotherapy treatment alone.

6370 of the patients had no history of arterial thromboembolic events (ATE's) before this trial started. From these 6370 patients a greater risk was shown for both ATE's and cardiac related death in those treated with bevacizumab compared to those treated with chemotherapy alone. The risk for ATE's over 3 years was 82% greater in those treated with bevacizumab. This correlates to an additional 3.5 events for every 1000 patients. The risk for cardiac related death over 3 years was 63% greater in those treated with bevacizumab compared to those treated with chemotherapy alone. No increased risk was shown for the development of heart failure or cardiomyopathy with bevacizumab treatment.

Overall, this study showed that bevacizumab increases the risk of arterial thromboembolic events compared to chemotherapy treatment alone. However, no link between bevacizumab and cardiomyopathy or heart failure was found. Researchers concluded that bevacizumab treatment only modestly increases the risk for cardiovascular events in elderly patients.

The risks associated with bevacizumab identified in this study were lower than those shown in previous studies. This may be due to the careful patient selection used in this study, and an older patient population compared to other studies.

Consult with your physician on the addition of bevacizumab to chemotherapy in the treatment of colorectal cancer, and how to reduce your risk for cardiovascular events during treatment.