Avastin Plus Chemo Carries Blood Clot Risk

[Christine]

A drug commonly added to chemotherapy for patients with some forms of cancer may be putting them at increased risk for blood clots in their arteries.

While researchers note deaths caused by these types of clots were rare in their study, they report the finding raises concerns about using bevacizumab (Avastin) for cancer patients.

Investigators from Genentech, Inc., makers of the drug, pooled the results of five previous studies involving more than 1,700 patients with metastatic colorectal, breast or non-small-cell lung cancer who received either combination treatment with chemotherapy and bevacizumab or chemotherapy alone. Nearly 4 percent of the patients in the combination group ended up with a clot in one of their arteries versus a little less than 2 percent of those in the chemotherapy alone group. Older patients and those with a history of blood clots were the most likely to have a clot.

The drug combo didn't appear to raise the risk for blood clots in the veins.

Foregoing bevacizumab to reduce the clot risk, however, could have other consequences. Researchers report the study also revealed a clear survival benefit for people on the combination treatment.

Still, authors note the study wasn't designed to investigate functional disabilities caused by the clots, and that leads them to stand by their concerns. They write, "The risk factors … identified in this study should be considered when making treatment decisions for individual patients."

SOURCE: Journal of the National Cancer Institute, 2007;99:1232-1239