BREAST CANCER
SCREENING and BREAST DENSITY Q & A:
Why
is breast density significant?
Dense breasts
contain more glandular and connective tissue. Less dense
breasts are mainly made up of fat tissue. Every woman has
different amounts of the different types of tissue in her
breasts. Breast cancer itself is made up of dense tissue.
This means that on a mammogram, a tumor is harder to spot
in dense tissue than in fatty tissue, because the tumor
looks a lot like the tissue around it. An analogy is often
used to describe the way dense tissue looks on film, "It's
like looking for a polar bear in a snow storm." Breast
cancers are readily seen in fatty tissue with up to 98%
sensitivity in film mammography.
Dense breast tissue itself is a risk factor for breast
cancer, with the risk 4-6 fold higher in women with
extremely dense breasts compared to fatty breasts, and
breast cancer is more likely to develop in denser areas of
the breast. Extremely dense (>75% dense) or
heterogeneously dense (51-75% dense) is present
in over half of women younger than age 50 years and
one-third of women age 50 years and
older.
How
often is cancer missed using standard film mammography, in
women with dense breasts?
With
film mammography, only 30-55% of breast cancers are
detected in women with dense breasts. That's why digital
mammography is so helpful. But regardless, mammography is
still an important piece of early detection. Please read
more below.
What is the prevalence of dense breast tissue in
women?
According
to the American College of Radiology Imaging Network
(ACRIN), 40% of all women undergoing screening mammography
have dense breasts. Breasts tend to become less dense as
women get older, but some women continue to have dense
breast tissue throughout life.
How
do you know if you have dense breasts?
Only
a mammogram can tell you for sure. Look for the terms
"heterogeneously dense or very dense", or "extremely dense"
in your mammogram report, which would indicate dense
breasts.
Most mammography reports use the following terminology to
categorize and describe breast density: describing four
different categories: (1) entirely fat; (2) scattered
fibroglandular densities; (3) heterogeneously dense; and
(4) extremely dense. The BIRADS classifications (American
College of Radiology Breast Imaging Reporting and Data
System) are used as a part of a radiologist's mammographic
assessment.
I have dense breasts; what do I do differently, if
anything?
It
depends on what you are doing now, but these are important
factors to consider in addition to nationally recommended
guidelines:
• Be
diligent with recommended monthly self breast exams and
yearly mammography and clinical exams.
• DO NOT skip a year with your annual mammogram. Have
prior exams sent to your current facility.
This will allow small changes to be seen.
This
is difficult if the previous year's film is not available.
• Go to a facility which specializes in breast
imaging, when possible, to make sure you have experts who
spend most of their time in this area.
• Go to a facility with digital mammography, when
possible, if you fit the guidelines (see below).
• Make sure you talk to your doctor about following up
any suspicious, palpable lump with further imaging.
• See a breast surgeon or surgeon specializing in this
area to follow up on suspicious areas, when unsure.
• Trust your intuition
• Ask for whole breast ultrasound screening if it is
offered at your facility and they have the equipment and
the expertise to do it.
What
is important about digital mammography and where can I have
it done?
In
a recent study with nearly 50,000 women participating, they
found that digital mammography was more sensitive than film
in finding cancers in women with dense breasts. Sensitivity
for women with dense breasts was only 55% for film and 70%
for digital, though these are in the most perfect research
conditions. Digital mammography allows the radiologist to
see images more clearly and to manipulate the image to see
it better (brightness, contrast, size, and orientation).
Digital mammography is becoming more widely available.
Because of it's popularity, you may need to request
it specifically
at
your imaging facility. Still, choosing a facility with
specialization in breast imaging is the most important
factor.
Did
the study say who would benefit most from digital
mammography?
Yes. Digital
mammography was significantly better in screening women who
fit any of these three categories:
• Under age 50 (no matter density)
• Any age with heterogeneously (very dense) or
extremely dense breasts
• Pre- or perimenopausal women of any age (defined as
having last menstrual period within 12 months of mammogram)
There
was no benefit for women who fit ALL the following
categories:
• Over age 50
• Don’t have dense breasts
• Not menstruating
How
is ultrasound important?
Ultrasound can
be used to evaluate masses that are hard to see on a
mammogram. Especially for women with dense breasts,
ultrasound is helpful in characterizing lumps or other
areas of concern. The Avon/ACRIN 6666 Trial showed that
when added to a screening mammogram, among women who were
at increased risk of breast cancer and had dense breast
tissue, ultrasound increased detection.
How
effective is it?
Ultrasound
has proven to increase the number of cancers detected by
67-100% in studies at single institutions. In addition,
smaller invasive cancers have been found with this
technology, usually before the cancer has spread to the
lymph nodes. For those at high risk for breast cancer who
are not recommended for MRI, it may improve detection of
breast cancer over mammography alone.
MRI is more sensitive and better for those at high
risk, but is costly
and insurance may not pay for it. Ultrasound is less
costly, doesn’t involve radiation, and may be easier
for many women to tolerate and obtain. Breast MRI’s
involve IV contrast being injected into the veins while
lying still for 30-60 minutes.
Why isn't ultrasound screening used instead of mammography?
Mammograms are
still important for women with dense breasts because they
are good at showing calcifications which are sometimes
produced by early breast cancers.
Ultrasound is used to diagnostically evaluate areas of
concern, right now.
Screening ultrasound looks at the
entire breast the way screening mammography does now, but
is not routine in most clinics. Most technologists are not
trained in whole breast ultrasound screening and when done,
is a lengthy process. Technologists are mostly trained
in diagnostic
ultrasound
screening, where they are looking at a single area of
concern.
The
use of screening ultrasound in high risk women has been
under investigation with the AVON/ACRIN 6666 trial with Dr.
Wendie Berg as the Principal Investigator. The first
results of the AVON/ACRIN 6666 trial showed that accuracy
in women with dense breasts was 78% with digital mammograhy
only, and 91% accuracy with mammograpy AND
screening
ultrasound.
Twenty eight percent more cancers were detected than with
mammography alone.
With any test,
there is a risk of finding something that needs to be
biopsied but is not due to cancer. You may want to check
whether your insurance covers screening ultrasound.
About a third of
U.S. facilities offer screening ultrasound, so it is
reasonable to request it, if offered by your breast imaging
facility (if they have good equipment and the expertise to
do it).
Other Breast
Cancer Facts:
•
Approximately 211,000 new diagnoses of breast cancer each
year
• Approximately 58,00 new diagnoses of non-invasive
each year
• 40,000 women will die this year of breast cancer-one
every 13 minutes in the U.S.
• Every 2 minutes someone is diagnosed
• Majority of breast cancers occur in women over 50,
but women at any age can have breast
cancer
The number one risk
factor for breast cancer is BEING A
WOMAN, the
second is GETTING OLDER!
Seventy per cent
of the time there are no identifiable risk factors
when a woman is
diagnosed. You can reduce your risk for disease and improve
the quality of your life, but there are no guarantees, or
fool-proof formulas for preventing disease.
Learn steps
to take for
early detection of cancer.
A special
thanks to Wendie Berg, MD, PhD, FACR, Breast Imaging
Consultant and Study Chair for the American
College of Radiology Imaging Network
(ACRIN) Protocol on Screening Breast
Ultrasound, for reviewing the material presented
for content and accuracy
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