The multi-billion-dollar cancer drug Avastin is no longer an approved treatment for breast cancer treatment, per a long-anticipated announcement made Friday by the U.S. Food and Drug Administration (FDA).

Avastin (bevacizumab, sold by Genentech/Roche) has been on the market since 2004 as a treatment for colon cancer. Following its lukewarm approval in 2008 for use against breast cancer, it came under increasing scrutiny for a lackluster track record with that disease.

"After reviewing the available studies, it is clear that women who take Avastin for metastatic breast cancer risk potentially life-threatening side effects without proof that the use of Avastin will provide a benefit, in terms of delay in tumor growth, that would justify that risk," FDA Commissioner Margaret Hamburg said in a prepared statement. "Nor is there evidence that use of Avastin will either help them live longer or improve their quality of life."

Side effects with Avastin include heart attack, high blood pressure and internal bleeding. The drug is a monoclonal antibody that limits the growth of new blood vessels that could sustain tumors.

The threat of pulling such a well-known and widely used therapy has sparked ire of many patients and advocates. During a June hearing, in which the FDA's Oncologic Drugs Advisory Committee voted unanimously to revoke the drug's approval for breast cancer, some breast cancer advocates spoke in favor of keeping the drug as an option for those fighting the disease.

"FDA recognizes how hard it is for patients and their families to cope with metastatic breast cancer and how great a need there is for more effective treatments," Hamburg said. Avastin had gained its FDA approval in part for this very reason, via the agency's accelerated approval program, which requires less rigorous efficacy data in exchange for ongoing study. The subsequent studies, done by Genentech, showed that the drug did no better than standard chemotherapy in improving the quality or length of life for patients. Such comparative-effectiveness research has been unpopular with some advocacy groups in the U.S., but researchers point out that large studies, rather than individual patient anecdotes, are crucial for determining the most effective care, a step that will also help rein in the nation's runaway medical costs.

"Patients must have confidence that the drugs they take are both safe and effective for their intended use," Hamburg said.

Avastin retains its FDA approval for treatment for some forms of brain, colon, kidney and lung cancer. And Genentech says it will continue to study the drug, in combination with the chemotherapy drug paclitaxel (Taxol, made by Bristol-Myers Squibb), by looking for biomarkers in subpopulations of women with breast cancer who might see more benefit.