April 18, 2006
Evista as Good as Tamoxifen for Breast Cancer: Study
By Maggie Fox, Health and Science Correspondent
WASHINGTON (Reuters) - The osteoporosis drug Evista works as well as tamoxifen in reducing the risk of breast cancer in high-risk older women, with fewer dangerous side effects, researchers said on Monday.
Both drugs reduce the risk of breast cancer in high-risk women past menopause by about 50 percent, the researchers said.
And the results of the 19,000-woman trial show that Eli Lilly and Co's Evista, known generically as raloxifene, is less likely than tamoxifen to cause certain types of blood clots, cataracts and uterine cancer, as well as more minor side effects such as hot flashes.
"It is clear that raloxifene is the winner of this trial," Dr. Norman Wolmark, head of oncology at Allegheny General Hospital in Pittsburgh, who led the trial, told reporters in a telephone briefing.
Tamoxifen, sold as a generic and by AstraZeneca Plc under the brand name Nolvadex, has long been prescribed to treat and prevent breast cancer.
Lilly said it would seek U.S. Food and Drug Administration approval to market Evista to prevent breast cancer. But doctors are free to prescribe the drug in any way they see fit.
Researchers said the findings should reassure women who know they have a high risk of breast cancer but who were afraid to take tamoxifen because of its widely known side effects.
"This is good news for women," said Dr. Leslie Ford of the National Cancer Institute.
Evista does not carry several of tamoxifen's most serious risks, the trial showed. Women who got Evista had 36 percent fewer uterine cancers and 29 percent fewer blood clots than women who took tamoxifen. Rates of stroke and heart attack were similar in both groups.
"Each has estrogen-like effects in some tissues and anti-estrogen effects in other tissues," Vogel said. Estrogen is linked to most breast cancer cases.
There will still be reason for many women to take tamoxifen, the researchers stressed. Evista has not been tested in women who have not yet passed menopause, for instance.
"Tamoxifen will remain the drug of choice for reducing breast cancer risk in pre-menopausal women," Vogel said.
Oddly, the women given Evista had a higher number of pre-cancerous lesions. The researchers said they were not sure why.
"As a result, the outcome of the study is not as clear cut as we might have hoped for," the American Cancer Society said in a statement.
"For now it will be very important for women with an increased risk of breast cancer to make an informed decision with the advice of their physician," the group said. "It is also important to note that while both drugs can prevent many breast cancers, neither has been shown to reduce the risk of death due to the disease."
Among the 9,745 women in the raloxifene group, 167 developed invasive breast cancer, compared to 163 of 9,726 women in the tamoxifen group.
The researchers estimated that 500,000 U.S. women take Evista for osteoporosis.
The drug had sales of $1.04 billion last year.
"This study is a positive for them, but it's kind of a non-event in terms of the share price. ... The market is saying show me something new," said Doug Christopher, an analyst at Crowell Weedon.
Lilly's shares fell 49 cents to close at $53.01 on the New York Stock Exchange.
The researchers estimated that 9 million to 10 million U.S. women are past menopause and at extra high risk of breast cancer because of a family history of the disease, an unusual number of breast lumps or other factors. Of them at least 2 million could prevent their breast cancer by taking tamoxifen without suffering side effects, they estimated.
Breast cancer is the second leading cause of cancer death among U.S. women, after lung cancer. More than 200,000 people are diagnosed and another roughly 40,000 die from it each year, according to the American Cancer Society.
(Additional reporting by Deena Beasley in Los Angeles)