Skip to content
My WebMD Sign In, Sign Up

Breast Cancer Health Center

Font Size

Tamoxifen, Evista Prevent Breast Cancer

Study Shows Tamoxifen Is a Little More Effective, but Evista May Have Less Risk
By
WebMD Health News
Reviewed by Laura J. Martin, MD

April 20, 2010 (Washington, D.C.) -- There are two good drug options for preventing breast cancer in high-risk women, and more women need to take advantage of them, doctors say.

Updated results from a large breast cancer prevention trial confirm that both the old standby tamoxifen and the osteoporosis drug Evista can substantially cut the risk of developing breast cancer in high-risk postmenopausal women.

Tamoxifen works a little better, but Evista may be a little safer, says study head D. Lawrence Wickerham, MD, of Allegheny General Hospital in Pittsburgh.

But "only 5% to 20% of the tens of thousands of women" who could benefit from the drugs use them, says Gabriel Hortobagyi, MD, a breast cancer specialist at the University of Texas M.D. Anderson Cancer Center in Houston who was not involved with the work.

Over 192,000 women, about 150,000 of whom were postmenopausal, were diagnosed with breast cancer in 2009, he says.

Updated results from the STAR (Study of Tamoxifen and Raloxifene) trial were presented at the annual meeting of the American Association for Cancer Research and published online by the journal Cancer Prevention Research.

Tamoxifen has been used for years to help fight breast cancer's return. In 1998, the FDA approved tamoxifen for use by women who hadn't had breast cancer but were at high risk of developing the disease.

Evista, known generically as raloxifene, is taken by about half a million women in the U.S. to prevent and treat osteoporosis, or thinning of the bones. In 2007, the FDA approved it for breast cancer prevention in some high-risk postmenopausal women based on earlier results from STAR and other trials.

As a breast cancer preventive, they're recommended for women at higher-than-average risk because of genetic mutations, family history, or other factors, including age over 60.

Tamoxifen vs. Evista

The updated analysis of the federally funded study involved nearly 20,000 postmenopausal women followed for almost seven years during and after treatment with either tamoxifen or Evista.

Earlier findings from the study, published in 2006, showed that both drugs reduced the risk of breast cancer by about 50% in high-risk, postmenopausal women. But Evista appeared to carry fewer risks of side effects, with lower rates of uterine cancer and clotting problems.

The new findings suggest that several years after treatment, which lasts about five years, tamoxifen is substantially better than raloxifene at preventing breast cancer.

About two years after treatment ended, tamoxifen reduced the risk of invasive breast cancer by 50%, while Evista cut risks by 38%.

Put another way, Evista was 76% as effective as tamoxifen, says Wickerham, who serves as a consultant to makers of both drugs.

Evista was about 78% as effective as tamoxifen at preventing noninvasive breast cancers (lobular carcinoma in situ and ductal carcinoma in situ).

Today on WebMD

Breast Cancer Overview
From self-exams and biopsies to reconstruction, we’ve got you covered.
Dealing with breast cancer
Get answers to your questions.
 
woman having mammogram
Experts don’t agree on all fronts, but you can be your own advocate.
woman undergoing breast cancer test
Many women worry. But the truth? Most abnormalities aren’t breast cancer.
 
Breast Cancer Treatments Improving
VIDEO
Resolved To Quit Smoking
SLIDESHOW
 
Woman getting mammogram
Article
Screening Tests for Women
SLIDESHOW
 
ovarian cancer overview slideshow
SLIDESHOW
serious woman
Article
 
what is your cancer risk
HEALTH CHECK
10 Ways to Revitalize Slideshow
SLIDESHOW