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February 23, 2004
Double Mastectomies Significantly Lower Risk of Breast
Cancer in Women Who Are Genetically at Risk, Penn Study
Shows
PROSE (Prevention and Observation of Surgical
Endpoints) is First Study to Quantify Risk Reduction
for BRCA1 and BRCA2 Gene Mutation Carriers
(Philadelphia, PA) - An international study led by researchers
from the Abramson Cancer Center of the University
of Pennsylvania has found that a prophylactic
double mastectomy - surgical removal of both breasts
to prevent a cancer before it occurs - can lower the
risk of developing breast cancer by 90 percent in women
genetically pre-disposed to the disease. This is the
first study to quantify the risk reduction for this
procedure and its impact on hundreds of thousands of
women in the United States who carry mutations in one
or both of the two genes - BRCA1 and BRCA2
- strongly linked to breast and ovarian cancer. Their
findings appear in the March 15th edition of the Journal
of Clinical Oncology.
“Women are still at risk for breast cancer after
any kind of mastectomy as some breast tissue remains
in the body after surgery,” said lead author Timothy
R. Rebbeck, PhD, Co-Program Leader of the Center’s
Cancer Epidemiology and Risk Reduction Program and an
Associate Professor of Epidemiology at Penn’s
School of Medicine. “Now that
we have quantified the benefit of a double mastectomy
for reducing the chances of breast cancer, women in
this high-risk group can make a better-informed decision
about having breast surgery in addition to other forms
of prevention, such as regular screening and/or other
preventive surgeries, including ovary removal.”
The study, called PROSE (Prevention and Observation
of Surgical Endpoints), followed 483 at-risk women from
11 sites in the United States, Canada, United Kingdom
and the Netherlands for over six years. Most of the
North American women chose not to have preventive, or
prophylactic, double mastectomies. Multiple study controls
were used to guard against research bias. Women who
chose to have prophylactic mastectomies were paired
with women in a control group based on type of mutation,
treatment center and year of birth within five years.
In addition, none of the participants had any previous
or current diagnosis of cancer upon entering the study.
Breast cancer was diagnosed in two of 105 women (1.9
percent) who had double mastectomies. The occurrence
of breast cancer was much greater in the control group,
with 184 of 378 women (48.7 percent) developing breast
cancer.
“The goal of future research is to refine these
estimates for women in specific situations: according
to the type of BRCA mutation; type of mastectomy
- different procedures remove varying amounts of breast
tissue; and the age and timing of surgery - many women
past their child-bearing years also choose removal of
their ovaries at the same time as their breast surgery,”
said Rebbeck. “The decision to undergo genetic
testing or have prophylactic breast surgery is a highly
personal one that should be discussed with a clinician
trained in counseling patients about the risks and benefits
of each preventive option.”
Study results also confirmed a large risk reduction
for breast cancer (95 percent) for women who also had
their ovaries removed.
“Genetically pre-disposed women should also consider
this procedure when evaluating their options for reducing
their risk of breast cancer,” said Rebbeck.
Funding for this study was provided through a research
grant from the National Institute on Health, Penn’s
Abramson Cancer Center, the Breast Cancer Research Foundation,
the Dana-Farber Women’s Cancers Program, the US
Department of Defense Breast Cancer Research Program,
the Utah Cancer Registry, the Falk Medical Research
Trust, the Utah State Department of Health, and the
Nebraska State Cancer and Smoking-Related Diseases Research
Program.
Close to 200,000 cases of breast cancer were diagnosed
in the US in 2001. The lifetime risk of any particular
woman getting breast cancer is about one in eight.
Between three and 10 percent of breast cancers may be
related to mutations in the genes BRCA1 and
BRCA2. Women can inherit these mutations from
their parents, and it may be worth testing for either
mutation if a woman has a particularly strong family
history of breast cancer. If a woman is found to carry
either mutation, she has a greatly increased chance
of getting breast cancer before age 70.
For
a printer friendly version of this release, click
here.
# # #
The Abramson Cancer Center
of the University of Pennsylvania
was established in 1973 as a center of excellence in
cancer research, patient care, education and outreach.
Today, the Abramson Cancer Center ranks as one of the
nation’s best in cancer care, according to US
News and World Report, and is one of the top five in
National Cancer Institute (NCI) funding. It is one of
only 39 NCI-designated comprehensive cancer centers
in the United States. Home to one of the largest clinical
and research programs in the world, the Abramson Cancer
Center of the University of Pennsylvania has 275 active
cancer researchers and 250 Penn physicians involved
in cancer prevention, diagnosis and treatment. More
information about the Abramson Cancer Center is available
at: www.pennhealth.com/cancer
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