More
Evidence Found Linking HRT To Breast Cancer Risk
Warning Continues
Against Combined HRT
Yet another study
has found an apparent increased risk of breast cancer in older
women who have taken combined hormone replacement therapy for
at least five years.
The latest study,
reported in the Journal of the American Medical Association
(JAMA), found that the increased risk held true regardless
of the pattern of progestin use, a hormone used in tandem with
estrogen.
"I think the new study
that we have just further characterizes risk of combined therapy,"
says Dr. Christopher Li, lead author of the study and researcher
at the Fred Hutchinson Cancer Research Center in Seattle.
Experts
Concur on Newest Evidence
Dr. Jay Brooks, chief
of hematology/oncology at the Ochsner Clinic Foundation in Baton
Rouge, La., says "This is just another piece of evidence that
shows that combined estrogen/progesterone hormone replacement
increases the risk of breast cancer.
"This is another example
of why these two types of medicines used together should not
be used, if at all possible, by women," Dr. Brooks says.
Hormone replacement
therapy (HRT) is prescribed to control symptoms of menopause,
such as hot flashes. Because estrogen increases the risk of
endometrial cancer in women, it is taken with progestin, which
mitigates that effect.
HRT can either be
taken continuously (estrogen and progestin every day) or sequentially
(estrogen daily and progestin for about 10 days every month).
Last summer, a large
study called the Women's Health Initiative
found that women taking combined hormone therapy experienced
a 26 percent increase in invasive breast cancer rates, compared
to women taking a placebo (inactive pill). Because of this and
other health risks, the trial using the two hormones together
was stopped.
Most of the women
participating in the WHI were taking continuous
hormone replacement therapy. The new study assessed both continuous
and sequential treatments by looking at HRT use in 975 women
who had been diagnosed with breast cancer, along with 1,007
"controls" -- women who were free of the cancer.
Study's
Detailed Analysis Helpful
Dr. Li and his colleagues
found a 50 percent increased risk of invasive ductal carcinoma,
which affects the milk ducts carrying milk to the nipple and
represents about 80 percent of all breast cancers.
There was a 170 percent
increased risk of invasive lobular breast cancer. Lobular breast
cancer is the second most common type of breast cancer and involves
the areas of the breast that contain the milk-producing glands.
Women who took combined
HRT had twice the risk of hormone-receptor-positive breast cancer.
These tumors need either estrogen or progesterone to grow.
Women who took "unopposed
estrogen" - or estrogen without progestin even for as long as
25 years - did not have any greater risk of breast cancer, the
study found.
"Unopposed estrogen
was not associated with breast cancer even if it was used for
a long period of time," Dr. Li says. "Combined therapy was associated
with an increased risk of breast cancer. It didn't matter whether
women took sequential or continuous. Both increased breast cancer
risk but only if they had used it for five years or longer."
Dr. Li says, "Now
that the WHI results have been published and there's a greater
sense among women that maybe they should stop taking HRT, we'll
be able to evaluate women who stopped HRT use. Does their risk
of breast cancer go back to baseline or will it stay elevated?"
Always consult your
physician for more information.
What
Are the Risk Factors for Breast Cancer
Any woman may develop
breast cancer. However, the following risk factors may increase
the likelihood of developing the disease.
Risk factors that
cannot be changed:
gender
Breast cancer occurs nearly 100 times more often in
women than in men.
aging
A majority of cases occur after age 50.
personal history of breast cancer
previous breast irradiation
family history and genetic factors
Having a close relative, such as a mother or sister,
with breast cancer increases the risk.
benign breast disease
previous breast biopsy in which the tissue showed atypical
hyperplasia
menstrual periods that began early in life
menopause began later in life
The most frequently
cited lifestyle-related risk factors:
smoking
not having
children, or first child after age 30
oral contraceptives
obesity and
a high-fat diet
physical inactivity
alcohol
long-term,
post-menopausal use of combined estrogen and progestin (HRT)
weight gain
and obesity after menopause
Environmental risk
factors:
exposure to
pesticides, or other chemicals
Always consult your
physician for more information.
Online
Resources
(Our Organization
is not responsible for the content of Internet sites.)
American
Cancer Society
American
Society for Clinical Oncology
Centers
for Disease Control and Prevention (CDC)
National
Cancer Institute (NCI)
National
Human Genome Research Institute (NHGRI)
National
Institutes of Health (NIH)
National
Women's Health Information Center
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August 2003
More
Evidence Found Linking HRT To Breast Cancer Risk
Experts
Concur on Newest Evidence
Study's
Detailed Analysis Helpful
What
Are the Risk Factors for Breast Cancer
Experts
Discuss Treatment in Women at High Risk for Breast and Ovarian
Cancer
Genetics
of Breast Cancer
Online
Resources
Experts
Discuss Treatment in Women at High Risk for Breast and
Ovarian Cancer
The Dutch authors say studies examining
the value of prophylactic surgery to prevent breast or ovarian
cancer in women at high risk for these cancers may have overestimated
or underestimated the benefits because of potentially unrecognized
biases in study design.
Scientists try to remove any elements
of bias from studies in order to obtain the most accurate findings
in a study.
Recognizing and understanding these
biases may help scientists improve the design of future studies
and better evaluate the results of previous studies, the authors
say.
The discussion comes in a recent
commentary in the Journal of the National Cancer Institute.
Women with certain mutations in
the breast and ovarian cancer susceptibility genes BRCA1 and
BRCA2 have an increased risk of developing breast and ovarian
cancer.
Both BRCA1 and BRCA2 are tumor
suppressor genes that usually have the job of controlling cell
growth and cell death.
Everyone has two BRCA1 (one on
each chromosome #17) and two BRCA2 genes (one on each chromosome
#13). When a person has one altered or mutated copy of either
the BRCA1 or BRCA2 gene, their risk for various types of cancer
increases.
Previous studies found prophylactic
bilateral breast removal is associated with an 85 percent to
100 percent reduction in breast cancer risk.
Other studies concluded that surgery
to remove the ovaries is associated with a similar risk reduction
for ovarian and breast cancer.
But these studies contain a number
of potential biases, according to the commentary. These include
familial-event bias, survival bias, detection bias, testing
bias, and confounding by other risk factors for breast and ovarian
cancer.
These biases need to given serious
consideration and warrant critical discussion about their potential
impact on study results.
"Only in this way can BRCA1/2 mutation
carriers, clinical geneticists, and treating physicians obtain
more accurate information about the true extent of cancer risk
reduction from prophylactic surgery.
"This valid estimate of risk reduction
may become even more crucial in the future when data become
available regarding the efficacy of new surveillance methods,
such as magnetic resonance imaging (MRI), and new chemoprevention
agents, such as raloxifene," the authors write in press statement.
Always consult your physician for
more information.
Genetics
of Breast Cancer
According to the National
Cancer Institute (NCI), the lifetime risk for a woman
to develop breast cancer is nearly 13 percent (one in eight),
while the lifetime risk to develop ovarian cancer is a little
greater than 1 percent (one in 70).
Approximately 5 percent to 10 percent
of breast and ovarian cancers are due to known predisposing
genetic factors. This means that the majority of breast and
ovarian cancers are, in fact, not inherited.
A gene is a basic unit of heredity
that determines a person’s traits. Genes are located on
one of the 46 chromosomes housed within cells that make up all
of the tissues of the body. They come in pairs, and work together
to make proteins. One member of the gene pair is inherited from
the mother, and one from the father.
Cancers develop due to alterations
(mutations) in genes. When an alteration or mutation in a gene
is present in the eggs and sperm, also called germ cells, it
is referred to as a “germline mutation.” When a
germline mutation is inherited it is present in all body cells.
Only a small percentage of cancers
involve inherited mutations that are passed from generation
to generation.
The majority of cancers can be
attributed to acquired mutations.
“Acquired” means that
the mutations occur only in the tissue that is affected by cancer
and are not present in all cells of the body. Acquired mutations
are not inherited and are not passed down to our children.
Always consult your physician for more information.
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