Hormone
Pills May Spur Breast Cancer
Tue Jun
24, 6:37 PM ET
By LINDSEY TANNER,
AP Medical Writer
CHICAGO - Estrogen-progestin
pills may cause an aggressive form of breast cancer (news - web
sites) and make it harder to find Tumors until they have reached
a later, less-curable stage, according to one of the biggest,
most authoritative analyses yet. The study is part of a run of
bad news recently about the hormones routinely taken by millions
of women after menopause.
"Hopefully, it
will convince women to reconsider," said Dr. Susan Hendrix
of Wayne State University in Detroit, a co-author of the new analysis.
"We've got to find a better way to help women with their
menopausal symptoms."
Some previous studies
suggested breast tumors might be less aggressive in hormone users;
other studies indicated the opposite. Previous research also suggested
that hormones might make breast tissue more dense, hindering the
detection of tumors.
To try to answer the
questions more definitively, the researchers took a closer look
at data from the government's landmark Women's Health Initiative
study, which was halted last summer after it was found that estrogen-progestin
pills raise the risk of heart attack, strokes and breast cancer.
While last summer's
findings led many women to stop taking hormones, an estimated
3 million women still use them, primarily to relieve hot flashes
and other symptoms of menopause.
The latest findings
appear in Wednesday's Journal of the American Medical Association.
The analysis involved
16,608 women ages 50 to 79 who used either combined hormone treatment
or dummy pills for an average of five years.
As of January, breast
cancer had developed in 245 women who used the combined hormone
treatment and in 185 women who had taken dummy pills.
Hormone users' tumors
were larger at diagnosis, 1.7 centimeters on average versus 1.5
centimeters in placebo women. Tumors had begun to spread in 25.4
percent of hormone users, compared with 16 percent of placebo
women.
The researchers said
this appears to mean that in women on estrogen-progestin, the
tumors both grow faster — that is, they are more aggressive
— and escape detection longer.
Overall, women on
both hormones faced a 24 percent increased risk of breast cancer
— equal to eight extra cases of cancer per year for every
10,000 women taking the pills.
The increased risk
did not appear in the first two years of treatment. But Hendrix
said the tumors may have been present early on but were not detected
until later because of hormone-induced breast density.
The new analysis did
not examine breast density. But researchers think progestin may
be the culprit because it can cause breast cells — both
normal and abnormal — to proliferate, an effect that may
be accentuated when the hormone is combined with estrogen.
Wyeth Pharmaceuticals,
maker of the Prempro pills used in the study, said hormones remain
an appropriate therapy when used at the lowest possible dose for
the shortest possible time.
The latest analysis
is by far the most conclusive, said Dr. Peter Gann, an associate
professor of preventive medicine at Northwestern University who
was not involved in the study.
It "further worsens
the news for long-term hormone replacement therapy. It suggests
the excess breast cancer risk is not trivial," Gann said.
Last summer's Women's
Health Initiative findings shattered long-held beliefs that hormones
are good for women's hearts. Last month, another analysis of data
from the study found that instead of sharpening the mind, hormones
may double the risk of Alzheimer's and other forms of dementia.
A second, smaller study
in Wednesday's journal also confirmed a link between combined
hormone treatments and breast cancer and suggested estrogen-only
treatment may be safer.
The study involved
975 Seattle-area women ages 65 to 79. The greatest breast cancer
risk was in women who used estrogen-progestin for at least five
years, even if they took the progestin component only some days
a month.
Those who used estrogen
alone, even for 25 years or longer, showed no appreciable increased
risk, according to the study, led by Dr. Christopher Li of Fred
Hutchinson Cancer Research Center in Seattle.
Estrogen alone is recommended
only for women with hysterectomies because it can cause uterine
cancer unless balanced by progestin.
The researchers said
more definitive answers will come from the continuing estrogen-only
part of the Women's Health Initiative study.
___
On the Net:
JAMA: http://jama.ama-assn.org
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