Avastin linked to vein-clotting risk

Genentech Inc.’s Avastin, widely prescribed for colon cancer and some lung tumors, was linked to significantly higher rates of vein clotting in an analysis of earlier studies.

Patients who got the drug were 33% more likely to have blood clots develop in their veins than those who didn’t receive it, said researchers led by Shenhong Wu, a cancer specialist at Stony Brook University in Stony Brook, N.Y.

Avastin, Genentech’s top-selling drug, with $2.3 billion in 2007 U.S. sales, bears a warning for high risk of clots in arteries. Genentech is based in South San Francisco.