Birth Control Pill Raises
Breast Cancer Risk for Some
Study finds younger women
with a gene face higher odds of disease
Women who have one of
the breast cancer genes and take oral contraceptives for five or
more years increase their risk of developing early-onset breast
cancer, a new study finds.
Researchers looked at
the history of birth control pill use in 2,600 women who had mutations
in either the BRCA1 or BRCA2 gene, the so-called cancer susceptibility
genes. Half of them had developed breast cancer and half had not.
Increased
Breast Cancer Risk Found Among BRCA1 Carriers Taking Oral Contraceptives
Women with BRCA1 mutations—but
not BRCA 2—who used oral contraceptives for five or more years
had a 33 percent increase in breast cancer risk compared with BRCA1
carriers who had never used the pill, says study author Dr. Steven
A. Narod, a professor and chairman of breast cancer research at
the University of Toronto. The research appears in a recent issue
of the Journal of the National Cancer Institute.
Narod's team also found
an elevated risk in those BRCA1 carriers who used the pill before
age 30 and who first used oral contraceptives before 1975, when
typical doses were higher than in more recent formulations. The
longer they used the pill, the higher the risk.
The average age of diagnosis
for the women with BRCA1 gene mutations who developed breast cancer
was 38.6.
Narod puts the elevated
risk in perspective this way: In the general population, women have
a 9 percent lifetime risk of breast cancer. "Women who are BRCA1
carriers and do not take the pill ever have about a 60 percent lifetime
chance of breast cancer," he says. "Women who are BRCA1 carriers
and do take the pill for five years have an 80 percent chance. That's
my interpretation of our findings."
To incur the increased
risk, he adds, they had to begin taking it before age 25.
Facing
Tough Decisions About Oral Contraceptive Use
Women who carry the genes
face tough decisions about oral contraceptive use. Research suggests
long-term use of the pill is associated with a modest increase in
the risk of early-onset breast cancer even in the general population,
but oral contraceptives are also found to be protective against
ovarian cancer risk, which has also been found to be elevated among
those with the breast cancer mutation genes.
Other experts praise the
study and say it will give them something solid to point to when
they are asked about the best course of action for BRCA1 and BRCA2
carriers.
"It's a very large study,
and that makes the information more applicable," says Monica Alvarado,
a certified genetic counselor at the University of Southern California/Norris
Comprehensive Cancer Center in Los Angeles. The women were recruited
from 52 genetic testing centers in 11 countries. "Prior to this,
we were able to tell women [with the gene mutation] that taking
the birth control pill reduces ovarian cancer risk but we didn't
know what it meant for breast cancer risk. All we could say was
there was a suspicion [that it increased risk]."
"We always have to be
careful [about making recommendations] based on one study," Alvarado
says. "But it's the first time we have any real data from a large
study to present to our patients."
Leslie Bernstein, an epidemiologist
and professor of preventive medicine at the University of Southern
California Keck School of Medicine, calls the study a critical paper.
"It's what we would have predicted based on other [smaller] studies,
including one we did," she says.
"It's a very well-done
study," adds Bernstein, who has studied the association between
physical activity and cancer reduction risk for several years. Like
Alvarado, she is reluctant to make recommendations based on one
study.
Always consult your physician
for more information.
HRT
Raises Risk of Lobular Breast Cancer
Study ID's type
of tumor tied to combined therapy
The National Institutes
of Health (NIH) pulled the plug on a massive
study earlier this year after women taking combined hormone therapy
were found to have an increased incidence of breast cancer.
Now a new study has identified
which type of breast cancer may be associated with the combined
hormone replacement therapy, or that which includes estrogen and
progestin.
Research appearing in
the Dec. 15 issue of the journal Cancer finds that
women on combined hormone therapy are at an increased risk for lobular
breast cancer.
Lobular and ductal breast
cancer are two of the more common forms of breast cancer. Although
lobular carcinoma is less aggressive than ductal, it has been on
the rise since the 1980s. The use of combined hormone replacement
therapy increased during the same time period, leading some to speculate
that it might be responsible for the increase.
"It's kind of a bad news/good
news thing," says Janet Daling, lead author of the study and a professor
of epidemiology at Fred Hutchinson Cancer Research Center in Seattle.
"[Lobular carcinoma] is a little more difficult to diagnose because
you don't pick it up as often on mammograms, but it has a good prognosis.
It appears to be highly related to the continuous combined hormone
therapy."
Hormone replacement therapy
(HRT) is taken by women to relieve symptoms of menopause. While
the hormone estrogen is actually responsible for reducing hot flashes
and vaginal dryness, it also increases the risk of cancer of the
uterine lining. Adding progestin to the mix effectively eliminates
that risk.
This study, called the
Women's Contraceptive and Reproductive Experiences (CARE) Study,
looked at approximately 4,500 postmenopausal women aged 35 to 64
who had been diagnosed with their first incidence of breast cancer.
They were compared to a control group of postmenopausal women who
had no history of breast cancer.
In interviews, all of
the women were asked to recall information on various aspects of
their medical history, including type of hormone therapy used, pattern
of use, dose, and total duration.
Women who used combined
hormone replacement therapy for six months to five years were 1.6
times more likely to get lobular carcinoma. Women who used it for
more than five years were twice as likely to be diagnosed with the
cancer, compared with women who never used it.
The risk was also greater
with continuous hormone therapy, or that which is delivered daily
for 25 or more days each month. Women on this type of hormone replacement
therapy for five years or more had a 2.5 times greater risk of lobular
breast cancer. After adjusting for the age at which menopause began,
the increase rose to 3.2 times.
Sequential combined hormone
replacement therapy was associated with a 1.5 times greater risk
for lobular cancer. "There was very little risk with sequential
HRT," Daling says.
A
Word of Caution
Dr. Clifford Hudis, chief
of the breast cancer medicine service at Memorial Sloan-Kettering
Cancer Center in New York City, cautions against giving too much
weight to the findings. This latest research was a case-control
study in which women were asked to remember details of their history,
and there was no actual control over the dispensing of the medication.
The gold standard in medical research remains the prospective randomized
trial. "This is the highest standard because presumably bias doesn't
influence who takes or doesn't take the medicine," Hudis says.
The results of this study
apply only to women under the age of 65. Daling has just finished
another study looking at women aged 65 to 79 and, in this group,
sequential HRT seemed to play a larger role.
Estrogen alone did not
appear to affect the risk of breast cancer.
Always consult your physician
for more information.
Online
Resources
(Our Organization is not
responsible for the content of Internet sites.)
American
Cancer Society
CA:
A Cancer Journal for Clinicians
Journal
of the National Cancer Institute
National
Alliance of Breast Cancer Organizations
National
Breast Cancer Coalition
National
Cancer Institute
Radiological
Society of North America
|
January 2003
Increased
Breast Cancer Risk Found Among BRCA1 Carriers Taking Oral Contraceptives
Facing
Tough Decisions About Oral Contraceptive Use
HRT
Raises Risk of Lobular Breast Cancer
A
Word of Caution
Can
Mammograms Spot Heart Disease?
Online
Resources
In Other Breast Health
News:
Can
Mammograms Spot Heart Disease?
Mammography makes headlines
as a screening test for breast cancer, but the technology may do
double duty as a predictor of heart disease.
Women whose mammograms
spot calcium deposits in their breast arteries are more vulnerable
to heart attacks and other fallout of cardiovascular disease than
those with clean vessels, new research has found. While the calcifications
in the breast do not harm the heart, they appear to echo narrowing
of the coronary arteries that feed the pump.
"Most people don't worry
about [the deposits] because they're not cancer," says Dr. Kirk
Doerger, a radiology resident at the Mayo Clinic and a collaborator
on the research. "But now we're finding that they do have some importance."
In 1998, for example,
Dutch physicians found that women with calcified breast arteries
faced a sharply higher risk of cardiovascular death, especially
if they had diabetes. And last year, Israeli scientists also found
the deposits, which increase with age, increased the risk of cardiovascular
disease in women—enough to lead the researchers to conclude
that mammography might be an inexpensive and effective screening
tool for heart and vessel problems.
However, the latest study
cannot make so strong a statement, says Doerger, who presented the
findings in December at the Radiological Society of North
America's annual meeting in Chicago.
Doerger and his colleagues
reviewed medical records of 1,803 women who had had mammography
as well as angiograms to examine their coronary arteries. They found
that after adjusting for a woman's age—which is closely linked
to cardiovascular illness—the presence of breast artery calcifications
on mammograms increased the risk of significantly narrowed blood
flow to the heart by 20 percent.
Smoking raised that risk
by 50 percent, and diabetes drove it up 210 percent, Doerger says,
so the effect is on the modest side. Still, he adds, "it's free
information" that radiologists now ignore.
Each breast has three
main arteries supplying blood. Calcifications on at least three
of those vessels raised the risk of coronary artery blockage, Doerger
says. However, more extensive breast artery lesions did not magnify
that risk, he says.
Turning mammography into
a tool to detect heart disease underscores a common misperception
about women's health. While many women express more fear of breast
cancer than cardiovascular disease, it is the latter that is more
likely to kill them.
Heart disease kills nearly
a half million American women each year, more than all cancers combined.
And nearly two-thirds of women who suddenly die of heart problems
have no previous symptoms.
Still, Dr. Susan Orel,
a radiologist at the University of Pennsylvania School of Medicine,
says she is not sure what to make of the new research.
Since the women already
had signs of artery trouble, the study group was "very biased" from
the start, she says. What's more, "you see [calcification of the
breast vessels] almost all the time in older women," diluting the
potential significance of the marker.
On the other hand, Orel
adds, calcifications on the mammograms of women in their 30s and
40s stir her concern.
Always consult your physician
for more information.
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