Aspirin Is Seen as Preventing Breast Tumors
May 26, 2004
By DENISE GRADY
Women who take aspirin regularly have a lower risk of
developing the most common type of breast cancer than those
who do not, researchers are reporting.
The finding is just one more lifesaving property credited
to a familiar and seemingly ordinary drug that has been
around for 100 years and is still far from fully
understood. Now, aspirin seems able to prevent breast
tumors stimulated by the hormone estrogen, which account
for 60 percent to 70 percent of all cases.
Women who took aspirin seven or more times a week had a 26
percent lower risk of developing those tumors than women
who did not take it, according to a report being published
today in The Journal of the American Medical Association.
The findings are based on a study in which researchers
compared women with and without breast cancer, and asked
each group's members whether they had taken aspirin. A
dozen previous studies had also suggested that aspirin
might ward off breast cancer, but the new study is the
first to find that only certain patients - women prone to
hormone-sensitive tumors - get the benefit. Laboratory
studies indicate that aspirin seems to prevent those
cancers by blocking an enzyme needed to make estrogen,
which can promote tumor growth in the breast.
But the scientists said it was too soon to recommend
aspirin just to prevent breast cancer in women who are not
already taking it for some other reason. They said more
research was needed to verify the findings and, if they
held up, to determine how much aspirin women should take,
and how often. The new study does not specify doses.
Aspirin can have serious side effects, including stomach
ulcers, gastrointestinal bleeding and brain hemorrhage.
"I think it's premature to recommend aspirin use
universally because of this study," said Dr. Mary Beth
Terry, lead author of the study, an assistant professor of
epidemiology at the Mailman School of Public Health at
But women already taking aspirin for other reasons may also
be protected against breast cancer, Dr. Terry said.
For women not already taking aspirin, she said, "the only
fair thing would be to have the woman take it or not based
on what her physician recommends given her overall health
Dr. Raymond N. DuBois, director of cancer prevention at
Vanderbilt University Medical Center and the author of an
editorial accompanying the report in the journal, said, "We
really don't recommend that women run out and start taking
aspirin, but some at very high risk should discuss it with
their physicians and see if it's the right thing for them
Women at high risk include those with a strong family
history of breast cancer or genetic mutations linked to the
disease. For them, Dr. DuBois said, aspirin's potential
benefits may far outweigh its risks.
Dr. Clifford Hudis, chief of breast cancer medicine at
Memorial Sloan-Kettering Cancer Center in New York, who was
not part of the study, said that aspirin and related drugs
like Vioxx and Celebrex were being studied at numerous
medical centers to see if they could prevent breast cancer.
They are being studied in other cancers as well.
Aspirin is cheap and ubiquitous, and Americans take 80
million tablets a day, to ease pain and fever and to
prevent and treat heart attacks. Studies have also
suggested that regular aspirin use can reduce the risk of
colorectal cancer by as much as 40 percent to 50 percent,
and although groups like the American Cancer Society do not
recommend aspirin for cancer prevention, some doctors
advise patients to take it anyway.
Doctors do not fully understand aspirin's role in
preventing various cancers. But by blocking enzymes called
cyclooxygenase 1 and 2, it may interfere with the growth of
intestinal cancer cells and the ability of tumors to
attract a blood supply. Blocking the enzymes also
interferes with the clotting ability of blood platelets,
and thus inhibits the blood clots that cause many heart
If the breast cancer findings hold up, aspirin could have a
substantial impact, researchers say. Breast cancer is the
most common cancer in women, with 215,990 new cases and
40,110 deaths expected this year. If 60 percent of the new
cases were estrogen sensitive, and 26 percent of those
could be prevented, that would mean nearly 34,000 fewer
"Any preventive agent that would provide this level of
reduction in risk would be very important," said Dr.
Michael J. Thun, the head of epidemiologic research for the
American Cancer Society.
But Dr. Thun warned that the cancer society does not
recommend aspirin or related drugs like ibuprofen for
cancer prevention. "The evidence remains incomplete, and
the drugs can have side effects that can be serious,
including gastrointestinal bleeding and intracranial
hemorrhage," he said.
Researchers estimate that for every 1,000 adults who take
aspirin for five years, from zero to two will have
hemorrhagic strokes as a result, and two to four will have
major gastrointestinal bleeding. Among people over 70, the
harmful effects may be two to three times as common.
The current study included 1,442 women with all forms of
breast cancer and 1,420 without the disease. Among the
women with cancer, 301, or 20.9 percent, had taken aspirin
at least once a week for six months or longer. Of the
healthy women, 345, or 24.3 percent had taken aspirin.
Like previous studies that suggested a protective effect of
aspirin, this one showed only an association and did not
prove cause and effect. But it provided a strong piece of
evidence because it made biological sense, the researchers
said: the finding that only hormone-sensitive tumors were
prevented meshed with the laboratory research indicating
that aspirin could block estrogen synthesis.
Eventually, aspirin may be added to the medicines now
prescribed to prevent recurrence in women who have had
breast cancer, said Dr. Andrew J. Dannenberg, an author of
the study and the director of cancer prevention at Weill
Cornell Medical College in Manhattan.
Researchers at the University of North Carolina and the
Mount Sinai School of Medicine in New York also
participated in the study.