Doctors are calling the results from a drug called Aromasin "game-changing." Aromasin is already approved to treat the recurrence of breast cancer. Now doctors think it may help prevent it in some women.
Aromasin cut the risk of developing breast cancer by more than half, without the side effects that have curbed enthusiasm for other prevention drugs, a major study found.
It was the first test in healthy women of newer hormone-blocking pills called aromatase inhibitors, sold as Arimidex, Femara and Aromasin, and in generic form. They're used now to prevent recurrences in breast cancer patients who are past menopause, and doctors have long suspected they may help prevent initial cases, too.
"I think this is an important study for women, and it may just lead the way to say that women could potentially prevent breast cancer," said "Good Morning America" Medical Contributor Dr. Marie Savard.
Savard is talking about the experimental drug Aromasin. A study of 4,500 post-menopausal women with risk factors for breast cancer revealed promising results.
"They had a 65-percent reduction in breast cancer risk and no serious side effects," said Savard.
Prevention drugs aren't advised for women at average risk of breast cancer. Those at higher risk because of gene mutations or other reasons already have two choices for prevention: tamoxifen and raloxifene. But they have side effects.
"Everything from uterine cancer to blood clots to even stroke and I think women and physicians have chosen not to use those drugs for the most part," said Savard.
The news was being celebrated at the huge ASCO cancer conference in Chicago over the weekend. Doctors feel they're on the edge of a new scientific era that will make a big difference to patients today.
In light of the study's findings, researchers say they will now give women who were taking a placebo drug the chance to switch to Aromasin.
Researchers say they expect to track participants for several years to monitor long-term effects.
The Associated Press contributed to this report.