From correspondent Rhonda Rowland

ATLANTA (CNN) -- Today, most women diagnosed with breast cancer beat the disease, largely because doctors can find it at an early, curable stage.

But women are still dying from breast cancer. It happens when the cancer metastasizes, or spreads to other parts of the body, such as the bones or major organs.

Now, a study in the New England Journal of Medicine shows breast cancer metastases could be prevented in at least half the cases, by taking -- believe it or not -- an osteoporosis drug from the same family of drugs as the well-known Fosomax.

"Until now, there's been no good way of treating people with bone metastases so this is a very important clinical complication of cancer," said Dr. Gregory Mundy of the University of Texas-San Antonio.

The study found the osteoporosis drug not only prevented cancer from spreading to the bone, but to other organs as well.

"It's such a surprising finding that we're still somewhat skeptical about it," said Emory University's Dr. William Wood.

The class of drugs is readily available. Women with osteoporosis have been taking them for years, and some of those women also have breast cancer.

Mary Hansen, for instance, was diagnosed with breast cancer 10 years ago. She has been taking a drug of the Fosomax type for two years, since she found out she had osteoporosis. Now, Hansen is encouraged she may be getting a double benefit from the drug.

"Oh, definitely," she said, "because I still have my left breast and I have mammograms every year for that, so sure, anything to give us hope."

Although researchers say more studies are needed to determine which one of the osteoporosis drugs works best, some doctors may start using them now:

"For people who are either showing evidence of breast cancer spread to bone or are considered to be at very high risk for breast cancer spread to bone, this appears to be an immediately useable treatment," Wood said.

The popular osteoporosis drugs appear safe, although they may cause stomach trouble in some women.

Emory University in Atlanta will be part of a government study to answer some of the remaining questions about the osteoporosis drugs and breast cancer. Certainly most women would welcome the chance to fight both diseases with one drug.