Study: Hormone-blocker slashes breast cancer risk

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Women at high risk of developing breast cancer because of family history or bad genes have a new option to help prevent the disease.

A study of 4,000 women found that a daily hormone-blocking pill cut the risk of developing breast cancer by more than half after five years of use.

"There are millions of women who could benefit from a drug such as anastrozole," says Dr. Therese Bevers, MD, of the Anderson Cancer Center. 

The drug is anastrozole, sold as Arimidex and in generic form. It can cause hot flashes, joint pain and other side effects, but these were nearly as common among women given dummy pills and are often due to menopause and aging.

Results were reported Thursday at a cancer conference in San Antonio.