November 20, 2008

Blood Clots in Cancer Patients

A drug meant to inhibit tumor growth may have a dangerous side effect.

Bevacizumab (Avastin) is prescribed to patients with colorectal cancer, non"“small cell lung cancer (NSCLC), renal cell cancer and breast cancer to inhibit angiogenesis -- the growth of new blood vessels, which plays a crucial role in the growth and metastasis of cancer. However, results of a new study shows bevacizumab caused a significant increase in venous thromboembolism -- blood clots in the deep veins of the legs or in the lungs -- one of the leading causes of illness and death in patients with cancer.

On average, patients being given bevacizumab showed an 11.9 percent incidence of venous thromboembolism -- 33 percent greater than those not taking the drug. The rates of blood clotting varied among different types of cancer, with the highest incidence among patients with colorectal cancer (19.1 percent) and the lowest among renal cancer patients (3.0 percent).

"The increased risk is observed not only for all-grade venous thromboembolism, but also for clinically significant high-grade venous thromboembolism," study authors wrote. "This finding will help physicians and patients to recognize the risk of venous thromboembolism with the administration of bevacizumab."

SOURCE: The Journal of the American Medical Association, 2008;300:2277-2285


On the Net: