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 ^[1], 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 ^[2].  In addition, the multiple myeloma clinical trial for Avastin can be found here ^[3].