Researchers, in a study published in the Journal of the American Medical Association, found an increased risk of veinous thromboembolism, or blood clotting, linked to treatment with Avastin (bevacizumab). A venous thrombosis is a blood clot that forms in the vein, a complication that affects many cancer patients. Concerns have arisen about whether or not Avastin contributes to the development of venous thromboembolism.

Avastin is a newly developed antibody commonly used in cancer treatments, including treatment of multiple myeloma. In a Phase 2 clinical trial for multiple myeloma, Avastin is reported to stop malignant cell growth by blocking blood flow to the cancer.

This study reports a 1.33 percent increased risk of blood clotting in patients treated with Avastin, compared with patients not treated with Avastin.  The risk was similar between patients taking a high and low dose of Avastin.

The original study can be found in the November 19 issue of the Journal of the American Medical Association here.  In addition, the multiple myeloma clinical trial for Avastin can be found here.