Avastin (bevacizumab) is the world's best selling cancer drug. Avastin is a drug that blocks the growth of new blood vessels. It is used to treat various forms of cancers including breast, kidney and lung. The drug is designed to hamper the creation of new blood vessels thus limiting the growth of malignant tumors by denying them nutrients. Research has shown that use of this drug can cause potentially life threatening side effects when taken. 

On November 18, 2011 the FDA announced it was revoking the approval of Avastin for breast cancer.  The FDA citing numerous studies decided the life threatening side effects without real proof that the drug slowed tumor growth was too big of a risk. According to the FDA the was no evidence that use of Avastin would help those with breast cancer live longer or have an improved quality of life. Avastin is manufactured by Genentech a subsidiary of Roche.