AURORA, Colo. -- The government delivered a blow to some desperate patients Friday as it ruled the blockbuster drug Avastin should no longer be used to treat advanced breast cancer.

Avastin is hailed for treating colon cancer and certain other malignancies. But the Food and Drug Administration said it appeared to be a false hope for breast cancer: Studies haven't found that it helps those patients live longer or brings enough other benefit to outweigh its dangerous side effects.

"I did not come to this decision lightly," said the FDA's commissioner, Dr. Margaret Hamburg. But she said, "Sometimes despite the hopes of investigators, patients, industry and even the FDA itself, the results of rigorous testing can be disappointing."

At an FDA hearing last summer, there was plenty of evidence of just how important the drug is to some.

"Why don't we matter?" said one woman. "We have small children to live for."

Dr. John Burke, an oncologist at the Rocky Mountain Cancer Center in Aurora, said adding Avastin to chemo treatments helps control tumors for longer periods of time.

"What it did not do was improve overall survival -- whether you live or die," said Burke. "And there was no proof of a benefit in terms of quality of life."

The FDA said Avastin's side effects are too risky. They include severe high blood pressure, hemorrhaging and heart failure.

"The conundrum is when I sit down with patients who have been getting this treatment and are doing great," said Burke.

Burke said he uses the drug in breast cancer patients, one of whose cancer has not gotten worse in two years.

"She's doing great," he said.

Burke said the drug can still be prescribed.

"It's still available. And I can give it to anybody I want," he said. "The problem becomes if the insurance companies stop paying for it because the drug is very expensive."

It costs about $90,000 a year by some estimates. Including infusion fees, a year's treatment with Avastin can reach $100,000.

Avastin remains on the market to treat certain colon, lung, kidney and brain cancers. Doctors are free to prescribe any marketed drug as they see fit. So even though the FDA formally revoked Avastin's approval as a breast cancer treatment, women could still receive it -- but their insurers may not pay for it. Some insurers already have quit in anticipation of the FDA's long-expected ruling.

However, "Medicare will continue to cover Avastin," said Brian Cook, spokesman for the Centers for Medicare & Medicaid Services. The agency "will monitor the issue and evaluate coverage options as a result of action by the FDA but has no immediate plans to change coverage policies."

The ruling disappointed patients who believe Avastin is helping to curb their incurable cancer.

"It's saved my life," said a tearful Sue Boyce, 54, of Chicago. She's taken Avastin in addition to chemotherapy since joining a research study in 2003. Her breast cancer eventually spread to her lungs, liver and brain, but Boyce said she is stable and faring well.

"So I'm hoping the insurance company will grandfather me in to continue taking it," she said.

The Avastin saga began in 2008, when an initial study suggested the drug could delay tumor growth for a few months in women whose breast cancer had spread to other parts of the body. Over the objection of its own advisers and to the surprise of cancer groups, FDA gave Avastin conditional approval -- it could be sold for such women while manufacturer Genentech tried to prove it really worked.

The problem: Ultimately, the tumor effect was even smaller than first thought. Across repeated studies, Avastin patients didn't live longer or have a higher quality of life. Yet the drug causes some life-threatening risks, including severe high blood pressure, massive bleeding, heart attack or heart failure and tears in the stomach and intestines, the FDA concluded. In two public hearings -- one last year and one this summer -- FDA advisers urged the agency to revoke that approval.

"The science is clear: Breast cancer patients are more likely to be harmed than helped by Avastin," said Diana Zuckerman of the National Research Center for Women and Families in Washington.

Genentech had argued the drug should remain available while it conducted more research to see if certain subsets of breast cancer patients might benefit, and some patients and their doctors had argued passionately for the drug.

"There certainly are patients who benefit tremendously," said Boyce's oncologist, Dr. Melody Cobleigh of Rush University Medical Center. "We'll just be battling with the insurance companies."

"For those not fortunate enough to be on Medicare or an insurance plan that covers it, it's a death sentence," Christi Turnage of Madison, Miss., said of the FDA's decision. Her breast cancer had moved into her lungs before she began Avastin three years ago and the spreading stopped, but Turnage said her insurer is ending coverage and she will seek financial help from Genentech's access program.

Hamburg said that she considered those arguments but that scientifically there are no clues yet to identify who those rare Avastin responders would be -- putting a lot of people at risk in order for a few to get some as-yet-unknowable benefit. She urged Genentech to do that research, saying the FDA "absolutely" would reconsider if the company could find the right evidence.

Genentech, part of Swiss drugmaker Roche Group, pledged to begin that research.

"We are disappointed with the outcome," said company chief medical officer Dr. Hal Barron. "We remain committed to the many women with this incurable disease and will continue to provide help through our patient support programs to those who may be facing obstacles to receiving their treatment in the United States."

The breast cancer organization Susan G. Komen for the Cure said that it respected the FDA's decision and that it was time for researchers to concentrate on finding so-called biomarkers that would tell which drug is right for which patient.

"Each type of cancer is very different from another in important ways, and in the end it's no surprise that Avastin's effectiveness may not be equivalent against all types of cancer," said Dr. Neal Meropol of University Hospitals Case Medical Center in Cleveland, who has long used Avastin for colon cancer.