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
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
In
This Issue:
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
Other
Resources:
John
F. Krey III Cancer Information Center
St.
John's Mercy Cancer Services
Find
a St. John's Mercy Physician
Breast
Health Information
Women's
Health Information
St.
John's Mercy Classes and Programs
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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