Older women at high risk for breast cancer may soon have a new treatment option.  Researchers have discovered that an osteoporosis drug is effective against the disease.  In fact, it is as good as the established breast cancer drug, and safer.

The drug Tamoxifen can reduce a woman's risk of breast cancer by about half, but it now has a challenger.  A nationwide U.S. study published in the Journal of the American Medical Association finds a similar breast cancer benefit from a drug used to reduce the risk of brittle bones.

"What we found was that the osteoporosis drug, raloxifene, was equally effective to the breast cancer treatment drug tamoxifen at reducing the risk of life-threatening breast cancer," said Dr. Vogel.

University of Pittsburgh physician Victor Vogel cites the main finding of a study of nearly 20,000 women who had reached menopause and were at high risk of breast cancer.  Besides finding that raloxifene is as useful as tamoxifen, Vogel's team also found it safer.

"Compared to tamoxifen, raloxifene was safer in terms of causing fewer uterine cancers and fewer life-threatening blood clots," he said.

Raloxifene also caused fewer cataracts, the clouding of the lens in the eyes.

But there were side effects with both drugs, which the doctors assessed in a second study of the same women.  Those on tamoxifen had more leg cramps, and gynecological and bladder control problems.  Women on raloxifene had more muscle and bone aches, pain during sexual intercourse, and weight gain.

Vogel's University of Pittsburgh colleague, Dr. Stephanie Land, says they asked the women how these unintended consequences affected them.

"What women are telling us is that although there are side effects with both of these treatments, that the side effects did not impact their overall quality of life in a negative way," said Dr. Land.

One of the raloxifene users was Marion Taube, who took it for five years as part of the two studies.

"I do not think I had any side effects - possibly leg cramping, but I do not know if that was related to the raloxifene or unrelated," said Marion Taube.

Researcher Stephanie Land says the studies are good news for women.  She expects U.S. government drug regulators to approve raloxifene for breast cancer in about one year.

"The overall and exciting news from this study is that women will have two choices," said Stephanie Land.

But Dr. Vogel says for older women, raloxifene may become the drug of choice.

"We concluded from the study that for postmenopausal women who were at increased risk, raloxifene was probably a better, safer choice for reducing the risk of life-threatening breast cancer," he said.