Evista May Help Prevent Endometrial Cancer

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Researchers say a drug prescribed for osteoporosis may protect against endometrial cancer.

Women who took Evista "had about half the risk of endometrial cancer than those not using the drug," says researcher Angela DeMichele, MD, associate professor of medicine at the Abramson Cancer Center at the University of Pennsylvania in Philadelphia.

Evista is a drug known as a selective estrogen receptor modulator (SERM). It has positive estrogen-like effects on bone and protects against osteoporosis — a bone-thinning disease.

However, the drug also blocks estrogen's effect on breast tissue. Some breast cancer cells grow in response to estrogen. SERMs reduce the risk of breast cancer by blocking estrogen receptors in breast cells.

DeMichele's study shows that Evista may be of benefit for endometrial-cancer protection in addition to its breast cancer protective effects. Endometrial cancer is a cancer of the lining of the uterus.

Evista Drops Risk of Cancer

For high-risk women, tamoxifen is the first and only drug approved for the prevention of breast cancer. But tamoxifen has been associated with an increased risk of endometrial cancer.

So doctors have been searching for alternative drugs for breast cancer prevention, including the bone-building drug Evista. The new study shows that Evista protects against endometrial cancer.

In DeMichele's study, women who used Evista were 50 percent less likely to have been diagnosed with endometrial cancer than women who never used the drug.

Overall, "users of tamoxifen were about three times more likely to develop endometrial cancer than users of Evista," DeMichele says. And women who took tamoxifen were about 50 percent more likely to develop the disease than nonusers, she says.

The study was presented at the annual meeting of the American Society for Clinical Oncology.

Ongoing Trial Could Open New Doors for Evista

The study included 547 women with endometrial cancer and 1,412 women without the disease.

The researchers were actually looking at genetic risk factors associated with endometrial cancer when they stumbled across the link to the drugs.

Despite the promising data, DeMichele stresses that Evista is approved only for the prevention and treatment of osteoporosis.

But experts say that could change after completion of a large trial sponsored by the National Cancer Institute, known as STAR, that is comparing the two drugs for their ability to prevent breast cancer.

If Evista is shown to be "better or even equivalent to tamoxifen in reducing the risk of breast cancer, Evista may prove to be the superior choice for women receiving chemoprevention," says Robert J. Mayer, MD, director of the Center for Gastrointestinal Oncology at Dana-Farber Cancer Institute in Boston and moderator of a news conference to discuss the study.

"If we can have a medication that can reduce the risk of breast cancer and not harm the uterine lining, that would be a big plus," he tells WebMD. "Plus you'll be getting two for the price of one — preventing breast cancer while also reducing osteoporosis."

The STAR findings are expected to become available in 2006. The study includes more than 19,000 postmenopausal women at increased risk of breast cancer and will determine whether Evista is as effective in reducing the chance of developing breast cancer as tamoxifen.

More than 40,000 women in the United States will be diagnosed with endometrial cancer in 2005, according to the American Cancer Society. More than 7,300 will die of it.

Evista is manufactured by Eli Lilly and Co., a WebMD sponsor.

ByCharlene Laino, reviewed by Brunilda Nazario, MD

SOURCES: 41st Annual Meeting of the American Society of Clinical Oncology, Orlando, Fla., May 13-17, 2005.

Angela DeMichele, MD, associate professor of medicine, Abramson Cancer Center, University of Pennsylvania, Philadelphia. Robert J. Mayer, MD, director, Center for Gastrointestinal Oncology, Dana-Farber Cancer Institute, Boston