Tamoxifen, Evista Prevent Breast Cancer
Study Shows Tamoxifen Is a Little More Effective, but Evista May Have Less Risk
WebMD News Archive
Tamoxifen vs. Evista continued...
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).
But women who took Evista "continued to have substantially fewer of the
serious side effects, including uterine cancers, clotting problems, and
cataracts, that seem to be barriers to tamoxifen use," he says.
There were 2.25 cases of uterine cancer per 1,000 women treated with
tamoxifen vs. 1.23 per 1,000 among women treated with Evista. There were 3.30
blood clot events per 1,000 women treated with tamoxifen vs. 2.47 per 1,000
among women treated with Evista.
"The absolute risk of these problems for any given woman is quite low,
regardless of treatment," says M.D. Anderson's Scott Lippman, MD.
There was no difference in death rates among the two groups. Neither of the
drugs has been shown to extend lives in high-risk women.
Who Is Considered a High-Risk Patient?
So which drug is better for which women? Both drugs are only for women at
high risk, doctors stress.
In the study, women were considered to be at high risk if their risk of
developing breast cancer over the next five years was 1.67% based on a simple
formula called the Gail model that takes into account age, family history, and
other factors. By definition, anyone over age 60 was at high risk.
But Hortobagyi says he probably wouldn't give the drugs to a woman in her
60s who is otherwise healthy based on age alone. "It's a discussion each woman
needs to have with her doctor. The more risk factors, the greater she will