Here's more on Tamoxifen:
Tamoxifen Is Not for Every Woman, Government
Cautions
By DAMARIS CHRISTENSEN
c.1998 Medical Tribune News Service
WASHINGTON -- Although the benefits of taking tamoxifen to
prevent breast cancer may be great, there are serious risks of
potentially life-threatening side effects with the drug, the National
Cancer Institute warned here Monday. As a result, each woman
should consider her individual risk factors and carefully discuss the
matter with her doctor before deciding to take the drug, officials said.
Late last month, the agency suspended a large trial because evidence
suggesting that tamoxifen could cut a woman's risk of developing
breast cancer by 45 percent was so compelling that continuing the trial
was unethical, said Dr. Richard Klausner, director of the NCI in
Bethesda, Md.
This action, which was to be reported Wednesday, was first made
public over the weekend when a woman in the trial spoke to the
Philadelphia Inquirer.
The more than 13,000 women in the trial are now finding out whether
they were receiving tamoxifen or an inactive placebo. Those who
received tamoxifen will be eligible to receive the drug for up to a total
of five years, the intended length of the study.
Those who received a placebo will be eligible to either receive
tamoxifen or perhaps to enroll in other cancer prevention trials, such
as a proposed trial to test tamoxifen against another, similar drug that
is believed to have fewer side effects, Klausner said.
''This is the first time in history we have shown that breast cancer can
not only be treated, it can be prevented,'' said Dr. Bernard Fisher, the
Pittsburgh-based scientific director of the National Surgical Adjuvant
Breast and Bowel Project, which conducted the tamoxifen prevention
trial.
There are ''innumerable questions'' left to answer - such as what
patients are most likely to benefit from the drug and how long the drug
should be taken for - but ''they don't challenge the results,'' he said.
The drug may not be appropriate for every woman, even those at high
risk of developing breast cancer, because tamoxifen may cause
life-threatening side effects, including blood clots in the lungs and a
higher risk of endometrial cancer, a cancer of the lining of a woman's
uterus, speakers said.
Previous research had shown that taking tamoxifen reduced the
chances of a breast cancer recurrence in women who had been
successfully treated for the disease. But it was unknown whether the
drug would benefit healthy women who were at higher-than-average
risk of developing breast cancer.
The breast cancer prevention trial enrolled 13,388 women from the
United States and Canada who were deemed to be at high risk of
developing breast cancer because they were 60 and older, had a
family history of the disease or had pre-cancerous breast tumors.
''If this benefit holds true we will be applauding as loudly as everyone
else,'' said Cynthia Pearson, director of the National Women's Health
Network, a Washington, D.C.-based advocacy group.
''But there are a number of questions that are still unanswered. The
majority of women who get breast cancer aren't in a high-risk group,''
she said. ''How do the costs balance out for them?''
Right now, the NCI has no answers. But the agency intends to
develop materials so that a woman and her physician can accurately
gauge the woman's risks of developing breast or endometrial cancer
and make an informed decision, Klausner said.
''This is a very important clinical trial result, [but] we don't have a
magic pill yet,'' said Dr. Lynn M. Schuchter, an associate professor of
medicine at the University of Pennsylvania Cancer Center in
Philadelphia and a spokesperson for the American Society of Clinical
Oncology.
''This is not a drug for every woman or even every woman at high risk
for developing breast cancer,'' she said. She emphasized that women,
who often overestimate their true risk of developing breast cancer,
should talk to a physician and weigh the benefits and risks before
taking tamoxifen in an attempt to prevent breast cancer.
Tamoxifen works by interfering with the activity of estrogen, a female
hormone that promotes the growth of cancer cells in the breast. As
such, it is called an anti-estrogen.
But in other parts of the body - such as the uterus - tamoxifen acts like
estrogen and, like estrogen, is known to increase the risk of
endometrial cancer.
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